Control of Emissions From New Highway Vehicles and Engines; Guidance on EPA's Certification Requirements for Heavy-Duty Diesel Engines Using Selective Catalytic Reduction Technology

Control of Emissions From New Highway Vehicles and Engines; Guidance on EPA's Certification Requirements for Heavy-Duty Diesel Engines Using Selective Catalytic Reduction Technology

Control of Emissions From New Highway Vehicles and Engines; Guidance on EPA's Certification Requirements for Heavy-Duty Diesel Engines Using Selective Catalytic Reduction Technology

Margo Tsirigotis Oge
Federal Register
June 7, 2011

[Federal Register Volume 76, Number 109 (Tuesday, June 7, 2011)]
[Proposed Rules]
[Pages 32886-32896]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-13851]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 86

[FRL-9315-2]

Control of Emissions From New Highway Vehicles and Engines;
Guidance on EPA's Certification Requirements for Heavy-Duty Diesel
Engines Using Selective Catalytic Reduction Technology

AGENCY: Environmental Protection Agency (EPA).

ACTION: Request for comments.

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SUMMARY: EPA is requesting comment on draft guidance and related
interpretations concerning the application of certain emission
certification regulations to those on-highway heavy-duty diesel engines
that are using selective catalytic reduction systems to meet Federal
emission standards. EPA will review the comments and provide final
guidance and interpretations in a future Federal Register document.

DATES: Any party may submit written comments by July 7, 2011.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2010-0444, by one of the following methods:
On-line at http://www.regulations.gov: Follow the on-line
instructions for submitting comments.
E-mail: a-and-r-docket@epa.gov.
Fax: (202) 566-1741.
Mail: Air and Radiation Docket, Docket ID No. EPA-HQ-OAR-
2010-0444, Environmental Protection Agency, Mailcode: 6102T, 1200
Pennsylvania Avenue, NW., Washington, DC 20460. Please include a total
of two copies.
Hand Delivery: EPA Docket Center, Public Reading Room, EPA
West Building, Room 3334, 1301 Constitution Avenue, NW., Washington, DC
20460. Such deliveries are only accepted during the Docket's normal
hours of operation, and special arrangements should be made for
deliveries of boxed information.
Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2010- 0444. EPA's policy is that all comments received will be included
in the public docket without change and may be made available online at
http://www.regulations.gov, including any personal information
provided, unless the comment includes information claimed to be
Confidential Business Information (CBI) or other information whose
disclosure is restricted by statute. Do not submit information that you
consider to be CBI or otherwise protected through http://www.regulations.gov or e-mail. The http://www.regulations.gov Web site
is an ``anonymous access'' system, which means EPA will not know your
identity or contact information unless you provide it in the body of
your comment. If you send an e-mail comment directly to EPA without
going through http://www.regulations.gov your e-mail address will be
automatically captured and included as part of the comment that is
placed in the public docket and made available on the Internet. If you
submit an electronic comment, EPA recommends that you include your name
and other contact information in the body of your comment and with any
disk or CD-ROM you submit. If EPA cannot read your comment due to
technical difficulties and cannot contact you for clarification, EPA
may not be able to consider your comment. Electronic files should avoid
the use of special characters, any form of encryption, and be free of
any defects or viruses. For additional information about EPA's public
docket, visit the EPA Docket Center homepage at http://www.epa.gov/epahome/dockets.htm. For additional instructions on submitting
comments, go to ``What Should I Consider as I Prepare My Comments for
EPA?''
Docket: All documents in the docket are listed in the http://www.regulations.gov index. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, will be publicly available only in hard copy.
Publicly available docket materials are available either electronically
in http://www.regulations.gov or in hard copy at the Air and Radiation
Docket, EPA/DC, EPA West, Room 3334, 1301 Constitution Ave., NW.,
Washington, DC. The Public Reading Room is open from 8:30 a.m. to 4:30
p.m., Monday through Friday, excluding legal holidays. The telephone
number for the Public Reading Room is (202) 566-1744, and the telephone
number for the Air Docket is (202) 566-1742.

FOR FURTHER INFORMATION CONTACT: Greg Orehowsky, Heavy-Duty and Nonroad
Engine Group, Compliance and Innovative Strategies Division, Office of
Transportation and Air Quality, U.S. Environmental Protection Agency;
1200 Pennsylvania Avenue, (6405J), NW., Washington, DC 20460. Telephone
number: 202-343-9292; Fax number: 202-343-2804; E-mail address:
Orehowsky.Gregory@epa.gov.

SUPPLEMENTARY INFORMATION:

I. Purpose

This Federal Register document describes and seeks public comment
on draft guidance for complying with adjustable parameter regulations
at 40 CFR 86.094-22 as they apply to certification of on-highway heavy-
duty diesel engines using selective catalytic reduction (SCR)
technology to meet emission standards for oxides of nitrogen
(NOX). This draft guidance includes EPA's interpretation of
relevant regulatory provisions in light of available information on
current and developing approaches for effective SCR controls. After
considering any public comments received, EPA will issue the guidance
and interpretations in the Federal Register, and will use them in
reviewing any application for certification application involving SCR
received on or after the effective date of the guidance. The draft
guidance contained in this document reflects the fact that
manufacturers of heavy-duty engines and operators of trucks have gained
significant experience in the design and use of SCR systems for these
engines, and this experience should be reflected in the certification
process. We invite public comment on the draft guidance and
interpretations set forth below.
Until the effective date of the final guidance and interpretations,
manufacturers should continue to refer to the regulations and the
existing guidance documents noted below and to work with their
certification representatives. We recognize that SCR technology will
continue to mature, and we anticipate that appropriate designs

[[Page 32887]]

for heavy-duty diesel vehicles and heavy-duty diesel engines using SCR
systems may continue to evolve as additional experience with the
technology is gained.
This draft document provides specific examples of how we interpret
existing certification regulations and how we intend to apply these
regulations to heavy-duty diesel engines using SCR systems, based on
the information available to us. These examples are not exclusive and
are to be considered examples. Manufacturers remain able to present
their own unique strategies that are not the same as the examples we
are providing, and such strategies will remain subject to our review
and approval under the certification regulations. Manufacturers must
still show EPA that they meet all statutory and regulatory requirements
when they apply for certification.

II. Overview

In promulgating the 0.20 gram per brake horsepower-hour
NOX standard for 2010 model year heavy-duty diesel engines,
based on a specified regulatory test procedure, EPA recognized SCR
technology as one potential approach for achieving the required
emission reductions. EPA identified several issues for manufacturers to
address in developing and applying SCR technology. Those issues related
largely to the technology's use of a chemical reducing agent to reduce
NOX emissions. The reductant is generally in liquid form,
which is referred to in this document as DEF (``diesel exhaust
fluid''). DEF is stored in a tank located on the vehicle and is
injected into the exhaust downstream of the engine. SCR technologies
require drivers to refill DEF on a regular basis and are dependent on
appropriately broad availability of DEF.\1\ EPA regulations governing
certification of engines generally require manufacturers to show that
emission control technologies are adequately designed to limit
adjustments that may increase emissions (``adjustable parameters,''
discussed in detail below). SCR is unique among emission controls in
that it requires on-going driver interaction to ensure proper operation
of the system.
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\1\ A Class 8 truck equipped with standard dual 150-gallon fuel
tanks can travel approximately 3,600 miles between DEF tank refills,
assuming a 20-gallon DEF tank and representative DEF dosing rate of
3 percent of fuel usage. DEF price varies depending on whether it is
supplied via bulk container (commonly used by fleets and growing
numbers of truck stops) or a 1 to 2.5-gallon jug. Current prices for
bulk DEF at a truck stop are generally less than $3.00 per gallon
and jug prices can be $4.00 or more per gallon.
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To comply with the NOX standard, most heavy-duty engine
manufacturers developed SCR systems because of their high efficiency in
reducing NOX emissions. A relatively unsophisticated SCR
system can achieve 60 percent reduction and a robust system can achieve
greater than 80 percent reduction. This enables engine calibrations
that increase fuel economy. Additionally, SCR technology has a
relatively lower cost compared to NOX adsorber technology.
In developing SCR systems, manufacturers consulted with EPA about
how SCR systems could be designed and what other steps would be needed
(e.g., concerning DEF availability) to allow SCR to be used consistent
with EPA regulations. Over a period of years, EPA has developed and
refined guidance to address how manufacturers could effectively address
issues related to compliance with the regulations for adjustable
parameters. Manufacturers have addressed the adjustable parameter
regulations by designing engines that employ warning systems for the
driver and engine operation-related inducements for drivers to refill
DEF tanks with proper DEF.
Manufacturers have also worked to increase DEF availability through
infrastructure development. DEF infrastructure and sales volume have
continued to grow since introduction of 2010 model year trucks equipped
with SCR systems. Initially, DEF availability was concentrated around
major truck routes, but has since increased in areas away from these
locations. DEF is now available for sale in every state at truck stops
and service facilities, and is available for delivery to fleet
locations, as well. To assist drivers in finding DEF, multiple
Internet-based DEF locator services have also been developed. Sales
volumes of DEF are increasing significantly and are believed to
correlate with the increased delivery and use of SCR equipped trucks.
Increasing demand supported by sales volume should continue to drive
the expanding infrastructure.

III. Relevant Regulatory Provisions

Under Section 203(a)(1) of the Clean Air Act, engines and/or
vehicles must be certified as conforming with all applicable
regulations before they may be introduced into commerce. Of particular
relevance for on-highway heavy-duty diesel engines using SCR technology
are the provisions that govern adjustable parameters at 40 CFR 86.094-
22.\2\ In particular, 40 CFR 86.094-22(e) authorizes EPA to determine
those vehicle or engine parameters that will be subject to adjustment
for emission testing purposes, and 40 CFR 86.094-22(e)(1) discusses how
the Agency determines which parameters are subject to adjustment.
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\2\ The regulatory provisions governing allowable maintenance at
40 CFR 86.004-25 and 40 CFR 86.094-25, and auxiliary emission
control devices, or AECDs at 40 CFR 86.004-2, 40 CFR 86.082-2 and 40
CFR 86.004-16 are also relevant to certification of engines using
SCR technology, but are outside the scope of this document.
Manufacturers should continue to refer to existing guidance noted
below covering these regulatory provisions.
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It is important for manufacturers to control the emissions
performance of an engine or vehicle over the full range of any
adjustable parameter in order to ensure that in-use operation is as
good as projected at the time of certification. When emission-related
parameters can be adjusted, there is a concern that the engine or
vehicle can be operated at settings other than the manufacturer's
recommended setting, possibly increasing emission levels.
If a parameter is subject to adjustment, the engine may be tested
over any point in the range of adjustment and must meet the emissions
standard through the range of adjustment. The Administrator determines
the range of adjustment for emissions testing based on whether the
means used to inhibit improper adjustment (e.g., limits, stops, seals)
are adequate. 40 CFR 86.094-22(e)(2) sets forth how EPA determines the
adequacy of the limits, stops, seals or other means used to inhibit
improper adjustment. For any parameter that is not adequately limited,
40 CFR 86.094-22(e) authorizes EPA to adjust the setting within the
physical limits or stops during certification and other compliance
testing. If a parameter is determined to be adequately inaccessible,
sealed, or otherwise inhibited from adjustment, the vehicle will only
be emission tested at the actual settings to which the parameter is
adjusted during production. 40 CFR 86.094-22(e)(2)(i) and (ii)
identifies certain types of parameters subject to adjustment, and
identifies criteria related to technology, time, or expense for
determining whether adjustment of the parameter is adequately limited.
These provisions indicate that the technology used to limit adjustment,
or the burden on the operator to make an adjustment (e.g., more than
one-half hour in time or more

[[Page 32888]]

than $20.00 in cost),\3\ can be adequate to determine that the
parameter is adequately limited and would not be treated as adjustable
outside of the specified range for purposes of emissions testing for
compliance with the standard. 40 CFR 86.094-22(e)(2)(iv) states that in
determining the adequacy of a physical limit, stop, seal, or other
means used to inhibit adjustment of an adjustable parameter, EPA will
consider the likelihood that settings other than the manufacturer's
recommended setting will occur during in-use operation of the vehicle
or engine, considering such factors as, but not limited to: (1) The
difficulty and cost of getting access to make an adjustment, (2) the
damage to the engine/vehicle if an attempt is made, (3) the effect of
settings beyond the limits, stops, seals, or other means on engine
performance characteristics other than emission characteristics, and
(4) surveillance information from similar in-use vehicles or engines.
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\3\ This cost is represented in terms of 1978 dollars. Adjusting
for inflation, this would equate to roughly $70.00 in 2011 dollars.
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The emission control efficiency of an SCR system is highly
dependent on the presence and quality of the reducing agent.
Consequently, it is critical that a SCR-equipped vehicle be designed so
that it is highly unlikely that the vehicle will be used without proper
reducing agent. Given that most SCR system designs store the required
DEF in a tank located on the vehicle and depend on the vehicle operator
to refill the tank with DEF, EPA has indicated in previous guidance
that manufacturers relying on SCR systems for emission control must
incorporate engine design elements that make it highly unlikely the
vehicle will operate for any substantial period without the appropriate
DEF. In practice, this has meant designing engines or vehicles to alert
operators of when the engine will run out of DEF, when the DEF is
inadequate, or if the SCR system is not properly operating due to
tampering or some malfunction. This has also meant designing engines or
vehicles with features that motivate operators to ensure proper use of
the SCR system, such as engine derates and vehicle speed inhibitors.
Engine derates and vehicle speed inhibitors alter important vehicle
performance characteristics, such as acceleration, maximum vehicle
speed attainable, and ability to maintain speed under various loads,
that are clearly noticeable to a driver.

IV. Prior Guidance

On March 27, 2007, EPA issued guidance regarding the certification
of light-duty and heavy-duty motor vehicles and heavy-duty motor
vehicle engines using SCR systems (CISD-07-07).\4\ The purpose of the
guidance was to discuss EPA's intended approach to certification of
engines using SCR technologies and to facilitate manufacturer planning
in advance of certification. EPA noted that several regulatory
requirements are uniquely relevant to the certification and
implementation of engines using SCR, specifically the regulatory
provisions dealing with allowable maintenance and adjustable
parameters. EPA suggested that an SCR system that requires the vehicle
operator to replenish DEF periodically is potentially an adjustable
parameter, and that unless operation of the vehicle without DEF was
sufficiently inhibited through built-in performance deterioration or
some similar system, vehicles using SCR could be treated as having an
adjustable parameter range including no DEF in the tank and could not
be certified if the vehicle would exceed emission standards without DEF
in the tank. EPA provided guidance regarding how engines using SCR
could be designed consistent with these regulatory provisions to allow
for certification of such engines. EPA provided examples of possible
sufficient inducements, including prohibiting operation if DEF is not
present and having vehicle performance degraded in a manner that would
be safe but onerous enough to discourage the user from operating the
vehicle until the DEF tank was refilled. EPA also highlighted the need
to assure that DEF would be available and accessible to operators and
suggested places where DEF could be made available, such as dealerships
and truck stops. We recognized that SCR technology was evolving and
that our guidance also might need to evolve.
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\4\ U.S. Environmental Protection Agency, Dear Manufacturer
Letter regarding ``Certification Procedure for Light-Duty and Heavy-
Duty Diesel Vehicles and Heavy-Duty Diesel Engines Using Selective
Catalytic Reduction (SCR) Technologies,'' March 27, 2007, reference
number CISD-07-07 (LDV/LDT/MDT/HDV/HDE), available at http://iaspub.epa.gov/otaqpub/display_file.jsp?docid=16677&flag=1.
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On February 18, 2009, EPA issued additional guidance (CISD-09-04)
to supplement CISD-07-07.\5\ This guidance provided additional details
regarding certification of heavy-duty engines with SCR systems.
Particularly, it outlined design elements that would make it highly
likely operators would replenish DEF prior to the tank being empty and
operators would not tamper with SCR systems. The guidance provided
specific examples of robust driver warnings and inducements to help
ensure operators addressed conditions such as low reductant level,
improper reductant quality, and tampered system components. EPA
continued to note the potential need for additional guidance or changes
in our approach for SCR certification.
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\5\ See docket number EPA-HQ-OAR-2010-0444-0018.
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On December 30, 2009, EPA revised CISD-09-04.\6\ The intent of this
revision was to clarify that CISD-09-04 was guidance and did not set
forth binding requirements. EPA revised the guidance and made clear
that manufacturers wishing to certify engines using SCR technology
should consult the revised guidance document as well as the guidance
provided in CISD-07-07. EPA also reminded manufacturers that they
should work with their certification representatives to provide EPA
adequate descriptions of the strategies that are incorporated in their
SCR systems in order to demonstrate compliance with EPA's certification
requirements as set forth in 40 CFR Part 86.
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\6\ U.S. Environmental Protection Agency, Dear Manufacturer
Letter regarding ``Revised Guidance for Certification of Heavy-Duty
Diesel Engines Using Selective Catalyst Reduction (SCR)
Technologies,'' December 30, 2009, reference number CISD-09-04
(HDDE), available at http://iaspub.epa.gov/otaqpub/display_file.jsp?docid=20532&flag=1.
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EPA has continued to monitor the development of SCR technology and
its effectiveness in achieving emission control in use. On July 20,
2010, in conjunction with the California Air Resources Board (CARB), we
conducted a public workshop to review existing guidance and policies
regarding design and operation of SCR-equipped heavy-duty diesel
engines.\7\ In particular, EPA reviewed approaches to designing SCR-
equipped engines to monitor and induce appropriate responses to
insufficient or improper DEF, as well as strategies regarding SCR
systems that are tampered with or defective. EPA developed a strawman
proposal regarding future certification of heavy-duty diesel engines
equipped with SCR technology,\8\ and opened a docket to allow public
comment regarding these issues.\9\ As part of the strawman, EPA
included approaches for engines

[[Page 32889]]

equipped with SCR, including designs that monitor on-board DEF supply
and induce action to avoid low DEF supply and operation with no DEF (or
an insufficient amount to allow proper dosing). EPA also discussed
detection of poor quality DEF, as well as warnings and inducements if
poor quality DEF is detected. In addition, EPA discussed designs for
engines equipped with SCR systems to sufficiently reduce the likelihood
that SCR system operation would be circumvented. EPA cautioned
manufacturers to review any element of design that could be tampered
with and prevent proper operation of the SCR system. Lastly, EPA noted
DEF freeze protection and infrastructure requirements, and requirements
regarding unregulated pollutants.
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\7\ See 75 FR 39251 (July 8, 2010).
\8\ See docket number EPA-HQ-OAR-2010-0444-0016. The strawman
proposal was not final guidance.
\9\ See 75 FR 39251 (July 8, 2010). Public comments received in
response to the public workshop are available in EPA's docket EPA-
HQ-OAR-2010-0444, available at http://www.regulations.gov.
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V. Experience to Date

A. EPA's Certification Program

For the 2010 and 2011 model years, EPA has certified a total of 71
on-highway heavy-duty diesel engine families with SCR systems produced
by 11 engine manufacturers. As part of the certification process,
engine manufacturers are required to disclose various aspects of the
SCR system designs, including elements of their system that may be
adjustable parameters. To date, manufacturers' designs have employed
driver warnings and inducements for low reductant level, poor reductant
quality, and tampered or malfunctioning SCR systems.
In order to ensure adequate availability of DEF for use with
manufacturers' engines, at the time of certification EPA reviews
manufacturers' plans for DEF availability and accessibility. EPA
expects manufacturers to have DEF available at their dealerships, to
encourage DEF availability at third-party locations, and to have an
emergency backup plan in case DEF is not readily available.
When manufacturers implement new emission controls, the engine
technology generally evolves and the manufacturers make improvements
over the course of initial model years as they develop and certify
engines and vehicles for each new model year. The process of
certification involves interaction between manufacturers and EPA
technical staff about the nature and effectiveness of emission controls
and often results in manufacturers modifying emission control
strategies based on feedback from EPA. In the case of SCR technology,
manufacturers have certified only a few model years of engines that
incorporate SCR technology, and EPA has seen maturing approaches to
implementing the technology. For example, from the 2010 to 2011 model
years manufacturers improved or developed new engine/vehicle diagnostic
software that provides more or better driver warnings and inducements
related to the SCR system. Similarly, manufacturers are also evaluating
various sensors that are expected to reduce the amount of time
necessary to detect poor quality DEF in future model years. As with
other new engine technologies, defects in the operation of SCR system
strategies (e.g., driver inducements) are sometimes discovered in the
field, and manufacturers initiate campaigns to fix the issues and
incorporate these fixes in current and new model year production
engines.

B. California Air Resources Board SCR Field Evaluation

The California Air Resources Board (CARB) recently conducted field
investigations within the State of California to evaluate
implementation of SCR technology for 2010 model year vehicles.\10\ The
investigations included: (1) A survey of DEF availability, (2) a survey
to determine whether drivers are using DEF or have tampered with SCR
components, (3) an evaluation of SCR driver inducements, and (4) an
evaluation of the potential emissions impact of improper SCR operation.
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\10\ California Air Resources Board, Report regarding ``Heavy-
Duty Vehicle Selective Catalytic Reduction Technology Field
Evaluation,'' May 2011, available at http://www.arb.ca.gov/msprog/cihd/cihd.htm.
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CARB conducted surveys of DEF availability in March 2010 and August
2010. Both surveys indicated that DEF is readily available at major
diesel truck stop refueling stations along major interstate highways in
California. In the first survey DEF was determined to be available at
85 percent of refueling stations, and in the second survey DEF was
determined to be available at 92 percent of refueling stations. In
addition, both surveys indicated that 30 percent of retailers that
normally supply parts for heavy-duty vehicles have DEF available. CARB
noted that as older engines are retired and an increasing number of
SCR-equipped engines enter into operation, the availability of DEF
should increase with demand. It concluded that DEF is currently being
offered in adequate supply for the relatively limited number of
vehicles using SCR.
In September 2010, CARB conducted random inspections of 69 trucks
equipped with 2010 model year engines to determine whether DEF was
being used, whether the DEF was of appropriate quality, and whether
driver warning indicators (i.e., warning lights, messages, or audible
alarms) were present. CARB found that all trucks were using DEF and
that the DEF was of appropriate quality. No DEF-related warning
indicators were active and there was no evidence of tampering with SCR
system components. Additionally, CARB solicited information from
drivers about their experience with locating DEF. Sixty drivers
indicated that they encountered no problem locating DEF, while nine
indicated they had minor problems locating DEF in California or in
other states. For those encountering problems, the issue was limited to
not being able to purchase DEF at a particular refueling station and
instead having to purchase it at a different refueling station. Sixty-
eight drivers stated that they never ran out of DEF while operating
their vehicles and only one driver indicated that he drove for only 10
miles with an empty DEF tank as indicated by the driver's gauge.
In the second half of 2010, CARB conducted an evaluation of SCR
inducements on three trucks equipped with 2010 model year engines and
SCR systems. The trucks evaluated were a Freightliner Cascadia equipped
with a 12.8-liter Detroit Diesel DD13 engine (Test Vehicle 1), a
Kenworth T800 equipped with a 14.9-liter Cummins ISX engine (Test
Vehicle 2), and a Dodge 5500 equipped with a 6.7-liter Cummins ISB
engine (Test Vehicle 3). Each truck was operated under various test
conditions to observe the operation of driver inducements and their
effectiveness in compelling the driver to take a particular course of
action. The conditions under which the trucks were operated included:
(1) Operation until the DEF tank was depleted, (2) operation with water
in the reductant tank instead of DEF, and (3) operation with a disabled
DEF system. CARB staff referenced the vehicle owner's manuals and the
February 2009 EPA guidance to ascertain the expected driver warning
indicators and inducement strategies that were expected in each
condition.
On Test Vehicle 1, the warnings and inducements were implemented as
expected. CARB deemed the warnings effective in drawing the driver's
attention to the need for SCR-related service. The initial inducement
incorporated in Test Vehicle 1 was a 25 percent engine torque derate
and a 55 mph speed limitation. CARB concluded that driving the truck
with these inducements was neither acceptable nor tolerable, especially
when trying to accelerate or driving up-hill, and would

[[Page 32890]]

likely cause a driver to refill with DEF or correct the SCR problem as
needed. If the initial inducement were ignored, the severe inducement
incorporated in Test Vehicle 1 was a 5 mph speed limitation, which
worked as designed. The only way to resume normal operation after the
severe inducement was to have the vehicle serviced by draining the
water out of the system, filling the reductant tank with DEF, and
having the system reset by an authorized service technician. CARB
determined that the inducements were effective for this vehicle because
the constant inducement strategies and risk of costly repairs would not
be worth the downtime and financial loss to the business when DEF could
simply have been added to ensure proper vehicle operation.
On Test Vehicles 2 and 3, the warnings and some inducements were
implemented as expected, but certain inducements were not. Test Vehicle
2 implemented the initial inducement (25 percent engine torque derate)
in response to DEF depletion, DEF contamination, and DEF tampering
conditions, but failed to implement the severe inducement (5 mph speed
limitation) in response to any of these conditions. Test Vehicle 3
incorporates an engine no-restart severe inducement after a 500-mile to
no-restart countdown. After the 500-mile countdown reaches zero and a
safe harbor event (key-off) is experienced, the truck should not
restart. The inducement worked as expected in response to DEF
contamination and DEF tampering conditions. In response to the DEF
depletion condition, Test Vehicle 3 started the 500-mile to no-restart
countdown as expected. However, after the countdown reached zero and
the truck was shut off, the truck successfully started the next day and
reset the countdown. On a subsequent restart attempt after the
countdown reached zero, the truck successfully implemented the no-
restart condition.
CARB contacted Cummins, the engine manufacturer for Test Vehicles 2
and 3, about the failures. Cummins was aware of and addressing the
issues underlying the failures. In the case of Test Vehicle 2, Cummins
in the second quarter of 2010 had implemented a correction on their
engine production line and in the third quarter of 2010 had begun a
voluntary recall of the engine family to correct the problem.\11\
Similarly, in the case of Test Vehicle 3, Cummins was aware of a DEF
heater malfunction that contributed to the final inducement not
initiating as expected and was already addressing the issue. CARB
concluded that for both Test Vehicles 2 and 3, the warnings were deemed
effective in drawing the driver's attention to the need for SCR-related
service. CARB also concluded that the inducements on Test Vehicle 2
were difficult to objectively assess due to a malfunctioning throttle
position sensor that was encountered during the testing. CARB concluded
that the inducements on Test Vehicle 3 were effective once the DEF
heater malfunction was corrected.
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\11\ Voluntary recalls are a typical method for manufacturers to
remedy emission-related problems they discover. Manufacturers are
required to report voluntary emission recalls to EPA and ARB, and
Cummins did so in this case.
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C. American Trucking Associations Survey

In 2010, the American Trucking Associations (ATA) through its
technical advisory group conducted a survey of 12 trucking fleets
operating across the United States regarding their experience operating
trucks with SCR-equipped engines.\12\ The surveyed fleets are some of
the largest in the country and operate an approximate total of 2,000
SCR-equipped trucks. The fleet owners indicated that they would
probably purchase approximately 5,900 SCR-equipped trucks in 2011.
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\12\ See docket number EPA-HQ-OAR-2010-0444-0019.
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None of the surveyed fleets reported any problems locating DEF and
none reported an engine derate, vehicle speed limitation, or no-restart
event caused by operation with an empty DEF tank. Similarly, no fleet
reported issues with the quality of DEF. There were six reported
instances of an engine derate resulting from circumstances other than
an empty DEF tank. Two of these instances were caused by malfunctioning
sensors and four were caused by melted DEF supply hoses. None of these
instances were associated with the behavior of the operator. Survey
respondents also reported a total of five instances of NOX
sensor malfunctions, none of which were related to driver
tampering.\13\ ATA's fleet survey indicates that drivers do not favor
inducements involving an engine power derate, especially if it occurs
while a truck under heavy load is driving up-hill.
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\13\ When a manufacturer determines that an emission-related
defect exists in 25 or more engines of the same class or category
and model year, they are required to file an Emission Defect
Information Report in accordance with 40 CFR 85.1901 et seq.
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D. Cummins Survey

In 2010, Cummins collected information from 47 different customer-
owned vehicles that were equipped with Cummins 11.9-liter and 15-liter
engines using SCR.\14\ The vehicles were equipped with data-loggers
that wirelessly transmit data to Cummins periodically on the operation
of those vehicles. At the time the data was gathered, the vehicles had
accumulated a total of more than 2.4 million miles of operation across
the United States. For approximately 99.7 percent of the operating
miles of the surveyed vehicles, the DEF level was above 10 percent of
tank capacity. For the remainder of vehicle operation:
---------------------------------------------------------------------------

\14\ See docket number EPA-HQ-OAR-2010-0444-0020.
---------------------------------------------------------------------------

DEF level was between 5 and 10 percent of tank capacity
for less than 0.13 percent of the operating miles (i.e., approximately
3,000 miles).
DEF level was between 2.5 and 5 percent of tank capacity
for less than 0.03 percent of the operating miles (i.e., approximately
740 miles).
DEF level was between zero and 2.5 percent of tank
capacity (a condition at which engines experienced derated performance)
for less than 0.04 percent of the operating miles (i.e., approximately
920 miles).
DEF level was at zero percent of tank capacity (a
condition at which engines experienced derated performance) for less
than 0.02 percent of the operating miles (i.e., approximately 520
miles).
In addition, DEF quality was unacceptable (i.e., a faulted
condition existed) for less than 0.18 percent of the operating miles
(i.e., approximately 4,400 miles).

E. Navistar EnSIGHT Report

In 2010, Navistar retained EnSIGHT, Inc. to test three 2010 model
year SCR-equipped trucks to analyze inducements provided for in EPA
certification guidance.\15\ The following three trucks were tested: (1)
One Freightliner Cascadia with a 15-liter Detroit Diesel engine, (2)
one Kenworth T-660 with a 15-liter Cummins ISX 15 435B engine, and (3)
one Dodge Ram 5500 crew cab flatbed with a 6.7-liter Cummins ISB 6.7
305 engine. As part of testing, the three trucks were operated with the
intent of circumventing the manufacturer-designed inducements, which is
in contravention to EPA tampering regulations.\16\
---------------------------------------------------------------------------

\15\ See docket number EPA-HQ-OAR-2010-0444-0015 for the August
2010 report. Navistar provided EPA with supplemental details on the
August 2010 report in a follow-up October 2010 report. See docket
number EPA-HQ-OAR-2010-0444-0022 for the October 2010 report.
\16\ Section 203(a)(3) prohibits tampering with emission
controls. Such actions are illegal, unless conducted as part of a
testing program covered by an Agency-issued testing exemption.

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[[Page 32891]]

Based on their testing program, EnSIGHT reported the following:
All trucks physically could be operated for extended
periods under an initial inducement. Provided the driver took
particular actions, final inducements could be avoided indefinitely.
For example, the Freightliner Cascadia was driven over 1,000 miles on
an empty DEF tank at a limited speed of 55 mph, which is the initial
inducement. As long as no more than 30 percent of the fuel tank
capacity (approximately 100 gallons) was added at any single refueling
event, the final inducement, a 5 mph vehicle speed limitation was not
triggered. The Kenworth T-660 was driven with an empty DEF tank and a
25 percent engine torque derate, which is the initial inducement. As
long as the engine was not shut off for more than a few minutes at a
time, the 5 mph vehicle speed limitation final inducement was not
triggered.
When DEF tanks were empty and water was added instead of
DEF, two trucks were able to run indefinitely. When the Dodge 5500 was
low on DEF and began its 500-mile to final inducement (i.e., no-restart
condition) countdown, the driver was able to fill the DEF tank with
water, start the truck, and drive normally. This action cleared the
500-mile countdown and the driver display indicated a full DEF tank. On
one test run, the truck displayed visual and audible warning signals
after 73 miles of driving with water in the DEF tank and eventually
displayed the 500-mile to no-restart countdown after 694 miles of
driving. Upon shutting off the truck after a total of 1,278 miles of
driving, a no-restart condition was encountered. On a subsequent test
run with water in the DEF tank, the truck was driven over 4,000 miles
and encountered no warning signals or inducements. The Freightliner
Cascadia was driven over 15,000 miles with only water in its DEF tank
and triggered no initial or final inducement.
SCR system components could be repeatedly disconnected and
reconnected to avoid particular inducements. On the Dodge 5500, the
driver was able to disconnect the injector electrical connector, which
would initiate a 500-mile to final inducement (i.e., no-restart
condition) countdown. As the mileage countdown continued, the driver
could reconnect the component and reset the 500-mile countdown. On the
Freightliner Cascadia, when electrical connections to the DEF injector,
gauge, or tank pump were unplugged, the truck was driven for over 1,000
miles prior to triggering an inducement.
Although the testing program was designed to intentionally
operate the trucks until final inducements were encountered, EnSIGHT
also provided an assessment of the impact of initial inducements on
driver behavior. They concluded that a 25 percent engine torque derate
would not induce a corrective response by the drivers, including when
the truck was fully loaded. With this level of derate, EnSIGHT's
drivers were able to operate the Freightliner Cascadia and the Kenworth
T-660 at speeds up to 55 mph and 65 mph, respectively. Of the Kenworth
T-660, EnSIGHT's drivers indicated that the truck could easily be
operated and was acceptable for typical driving for long periods of
time under derate.

F. DEF Infrastructure and DEF Quality

The DEF infrastructure and sales volume have continued to grow
since introduction of 2010 model year trucks equipped with SCR systems.
Initially, DEF availability was concentrated around major truck stops
and truck routes and 2.5-gallon jugs represented the common mode of
supply. Although very limited, bulk DEF dispensing typically utilized
small storage tanks located apart from the fuel islands at truck stops.
The refilling of fuel and DEF tanks at truck stops was also more likely
to require two separate purchase transactions.
The continually increasing DEF infrastructure and sales volume have
resulted in improved DEF availability along major truck routes as well
as other locations. ``AdBlue and DEF Monitor,'' a publication of
Integer Research, reports that DEF is available for sale in jug form in
every state.\17\ Integer Research also reports that DEF is available
for delivery to fleet locations in every state, as well. To assist
drivers in finding DEF, multiple Internet-based DEF locator services
have been developed. One of these services, DiscoverDEF.com, run by
Integer Research, recently announced that DEF consumption in the U.S.
reached 2.3 million gallons per month in December 2010 and that in
August of the same year consumption volumes increased 43% compared to
the previous month. Also, a number of suppliers reported sales volumes
doubling in September 2010 alone. These increases in DEF consumption
are believed to correlate with the increased delivery and use of SCR-
equipped trucks.
---------------------------------------------------------------------------

\17\ See docket number EPA-HQ-OAR-2010-0444-0021.
---------------------------------------------------------------------------

Increasing demand supported by sales volume helps drive the
continuing expansion of DEF infrastructure. The same locator service
recently reported that more than 100 truck stops in the U.S. and Canada
now have DEF available at the pump. Additionally, this service
maintains a list of over 3,000 locations that have packaged DEF, and a
majority of the locations are in the U.S. As truck stops such as Travel
Centers of America roll out on-island DEF dispensers, they usually
incorporate technology which allows for single transaction fuel and DEF
filling, which makes buying DEF quicker, more efficient, and customer-
friendly. On-island DEF dispensing typically requires truck stops to
utilize a mini-bulk system with at least 800-gallon above ground
storage tanks or even larger underground storage tanks. The transition
to larger tanks supports bulk purchases as well as cheaper end-user
prices for DEF. This information is consistent with the survey
information discussed above.
Regarding DEF quality, ISO 22241-1 sets forth generally accepted
industry-wide quality specifications for DEF that were developed by
vehicle manufacturers and other affected stakeholders. The American
Petroleum Institute (API) Diesel Exhaust Fluid Certification Program
(http://www.apidef.org) is a DEF quality licensing program intended to
ensure that DEF of known specifications and quality is available. We
understand that more than 20 of the largest producers of DEF are
participating in the Certification Program and that the associated DEF
Aftermarket Audit Program has also begun. In 2010, API tested all
licensed products and the vast majority of those products met the ISO
22241-1 specifications. Where deficiencies were found, API and DEF
manufacturers are working to identify the cause and helping to ensure
that future batches conform to the ISO specifications. Because of API's
Audit Program and its responsiveness to failed test results, we believe
good quality DEF is broadly and generally available. API's
Certification and Audit Programs were developed under the SCR
Stakeholder Group, an informal consortium of vehicle/engine
manufacturers, urea manufacturers, DEF blenders and distributors, and
associated technology companies. EPA has been an active participant in
the Stakeholder Group for several years. We also understand that the
Petroleum Equipment Institute, its members, and associated stakeholders
have developed Recommended Practices for the Storage and Dispensing of
Diesel Exhaust Fluid (DEF), which will provide useful advice to any
party

[[Page 32892]]

who stores and dispenses DEF. Given that the vast majority of DEF
production is accounted for in API's certification program and that the
follow-up audit program is showing high rates of conformance to the ISO
specifications, we believe these programs will be adequate to ensure
DEF quality.

VI. Reasons for Revised Guidance

Considering the developments in SCR-related technologies, DEF
infrastructure, and the other available information described above, we
believe it is appropriate to further refine our guidance to
manufacturers regarding certification of SCR-equipped engines to be
compliant with applicable regulations. As discussed in this section of
the document, on-highway heavy-duty diesel SCR systems introduced into
commerce to date have been highly successful in inducing operators to
refill DEF tanks on a timely basis and to avoid interfering with SCR
operation, with a few specific exceptions.\18\ At the same time, the
Agency believes it is appropriate to refine its guidance, particularly
as experience is gained with SCR in-use and as technology advances. We
seek comment on the draft guidance and interpretations presented here
and plan to incorporate what more we learn in the next version of the
guidance to be issued later this year.
---------------------------------------------------------------------------

\18\ It is worth noting again in this context that under Section
203(a)(3) of the Clean Air Act, tampering with SCR systems or other
emission controls is prohibited.
---------------------------------------------------------------------------

A. Current SCR Systems Are Highly Effective in Use

As trucks equipped with SCR systems have been introduced into U.S.
commerce, drivers have become familiar with this technology. Current
information concerning in use operation of SCR-equipped trucks,
including all of the studies and other information discussed above,
indicates that warning signals work correctly and that drivers do not
wait for SCR-related inducements to be triggered to ensure appropriate
and continuing operation of the systems. Specifically, the overwhelming
majority of drivers surveyed by CARB, ATA, and Cummins did not wait for
activation of warning indicators prior to refilling their DEF tanks
and, where warnings did occur, generally did not drive distances long
enough to lead to activation of inducements. Further, as the
infrastructure for making DEF available becomes even more widespread,
drivers will have increased and more convenient access to DEF when they
need it. As documented in part by CARB's survey, there are currently
few availability issues and those appear to stem primarily from limited
situations where DEF was not found at the first location at which it
was sought. As DEF infrastructure and supply continue to expand, EPA
also expects the price of DEF to decrease, in part because of the move
to bulk dispensing that is already underway. In addition, EPA expects
that the DEF quality assurance programs described above will make it
increasingly easy for drivers to find DEF which meets the
specifications necessary for proper operation of the SCR systems. The
strong indication from all of this evidence is that DEF warning systems
are working correctly, and that when warned, drivers have not continued
to drive distances long enough to lead to inducements. Inducements
appear to be triggered in very few cases.
Navistar's study and CARB's field evaluation provide some evidence
indicating that in some cases there have been issues related to SCR-
equipped engines and assurance of their proper operation. Navistar's
study identifies specific problems associated with the design or
manufacture of certain SCR-equipped engines, and outlines the
intentional actions taken by drivers employed by Navistar's contractor
in conducting the study. The study's findings are properly considered
in the context of all the available information on SCR operation. In
light of the investigations and surveys conducted by CARB, ATA, and
Cummins, EPA does not believe Navistar's findings reflect the overall
efficacy of SCR systems on heavy-duty diesel engines currently in
operation or the way they are actually used.
Most of Navistar's findings resulted from actions by the
contractor's drivers to intentionally circumvent the manufacturer-
designed inducements of the three test vehicles. For example, drivers
avoided triggering inducements associated with an empty DEF tank by
limiting refueling quantities or keeping the truck running when it
normally would be turned off. Both ways of circumventing the
inducements exact their own costs on drivers in terms of time,
convenience, and expense. To illustrate, never refilling above about
30% of the tank leads to approximately three times as many refueling
events, and the time and expense associated with this kind of
disruption detract from the efficient operation of truck operators, who
work in a competitive business. Navistar's contract drivers also
disconnected and reconnected various SCR system components as a means
of avoiding DEF inducements. Such intentional actions would be
considered tampering and are illegal.\19\ While it is possible that
drivers could intentionally take such actions to circumvent
inducements, manner of truck operation conducted in the Navistar study
is clearly not representative of the vast majority of truck operation,
as indicated by the CARB and ATA surveys. We do not think that the
marginal cost and effort involved in purchasing DEF provide sufficient
motivation for a driver to follow such inconvenient and risky courses
of action.
---------------------------------------------------------------------------

\19\ Such actions are illegal, unless conducted as part of a
testing program covered by an Agency-issued testing exemption.
---------------------------------------------------------------------------

We also do not agree with Navistar's view that initial inducements
are ineffective to produce corrective responses by drivers. ATA's fleet
survey indicates that drivers do not favor inducements involving an
engine power derate, especially if it occurs while a truck under heavy
load is driving up-hill. Thus, drivers are likely to maintain proper
SCR operation to avoid encountering these inducements. CARB's
investigation shows that most inducements functioned properly during
expected truck operating conditions and their assessment of the
effectiveness of initial inducements was contrary to Navistar's
findings. CARB determined that the inducements were effective because
operating in a way that avoids the inducement strategies and raise the
risk of costly repairs would not be worth the downtime and potential
financial loss to business. In fact, Cummins' survey, which included
some of the same 15-liter engines in Navistar's study, found that
surveyed trucks operated with DEF in their tanks for greater than 99.9
percent of their total operation. Cummins' survey also found that
trucks operated with unacceptable DEF quality for less than 0.18
percent of their total operation. This strongly indicates that the
inducements have the intended effect of motivating appropriate driver
behavior.
The report of Navistar's study found that some manufacturers'
designs did not adequately detect water in the urea tank and thus did
not prevent the driver from refilling the tank with something other
than DEF. Navistar and CARB findings on DEF quality detection were not
consistent in all cases. For example, Navistar found that initial and
final inducements for the Freightliner Cascadia equipped with the 12.8-
liter Detroit Diesel DD13 engine were not triggered when the DEF tank
was filled with water. During CARB's field investigation, both the
initial and final inducements were implemented for Test

[[Page 32893]]

Vehicle 1 as expected when the DEF tank was filled with water. CARB's
investigation discovered various production defects for Test Vehicles 2
and 3 that prevented the systems from working fully (as designed, the
systems appeared to have sufficient capabilities to detect and respond
to DEF quality problems). CARB followed up with Cummins and learned
that the manufacturer was aware of the performance problems and
addressing them in a manner consistent with regulatory provisions
governing defect reporting and repair.\20\ The defect reports submitted
by Cummins corroborated that the manufacturer was appropriately
responding to the problems. Additionally, Detroit Diesel informed EPA
that they knew of problems with their system and had developed an
updated software calibration to fix them as early as June 2010, prior
to Navistar reporting the results of their study. Detroit Diesel has
since begun addressing the problems on in use trucks consistent with
regulatory provisions governing defect reporting and repair. As noted
above, the problems with detecting water in the urea tank appear to be
related to defects in production of these engines, as opposed to
deficient designs. These production defects are being addressed in the
same manner that problems with new technology are addressed under EPA's
regulations.
---------------------------------------------------------------------------

\20\ See 40 CFR Part 85, Subpart T.
---------------------------------------------------------------------------

B. Regulations Should Be Applied in Light of Continuing Information and
Process Improvements

EPA's regulatory provisions for adjustable parameters are intended
to ensure that manufacturers design their emissions control system in a
way that makes it unlikely that they will be operated inappropriately.
It appears that manufacturer's past SCR designs and EPA's guidance have
resulted in highly effective controls to protect the operation of SCR
systems, as evidenced by the surveys and other data which show that
drivers are properly operating their SCR-equipped trucks. There have
been indications of specific problems with some engines in-use, and the
manufactures involved have been addressing them through production and
other improvements as the problems are identified. We believe it is
appropriate to evaluate the experience gained to date and to make
continuing, appropriate adjustments to our certification process for
SCR-equipped engines as technology evolves and in-use experience is
gained. EPA recognizes that development of even more robust sensors and
inducements does not negate past approaches implemented pursuant to
existing regulations. Rather, continual improvement is expected given
the mounting experience with, and the maturing of, SCR technology, and
the greater availability of DEF. As improved strategies and
capabilities for proper SCR operation become feasible, EPA may guide
their application to provide even further assurance that the technology
is operating as intended on SCR-equipped engines.

C. As SCR Technology Matures, Further Guidance Is Appropriate

Several developments in SCR technology allow continuing refinement
in SCR design. One area of potential improvement in design involves
sensors that can detect poor quality DEF. Current SCR system designs
incorporate NOX sensors to determine catalyst efficiency and
detect catalyst malfunction. Since the sensors are part of the system
design, they have also been used to detect poor quality DEF through
correlation of NOX emission rates with various
concentrations of urea. Urea quality sensors have been identified as a
means to help improve detection capabilities for poor quality urea.
They directly measure quality and appear likely to represent a quick
detection method for addressing quality concerns. Manufacturers are
currently evaluating the performance and durability of various sensor
designs.
Since the 2010 model year, manufacturers have also been refining
their engine/vehicle system diagnostics software to incorporate
additional capabilities for implementing SCR-related inducements. For
example, many manufacturers today have developed multiple triggers for
triggering inducements, including detection of refueling, extended
idling, and engine shutdown events. Incorporation of additional
inducement triggers into designs further decreases the likelihood of
improper operation of the SCR system. Manufacturers are also improving
their diagnostics software to ensure that SCR-related inducements
cannot be reset or erased by diagnostic scan tools available to the
general public or by disconnecting components in the field.
Many manufacturers are implementing improved designs in their 2011
model year engines/trucks that may be sold in the State of California.
After the July 2010 public workshop, CARB and EPA began encouraging
manufacturers to adopt the elements of design that were discussed. In
order to avoid the need for multiple engine/vehicle production designs,
manufacturers have often incorporated the design elements of vehicles
sold in California into their 49-state vehicles.
Improving sensor capabilities and inducement strategies should
present low risk and little burden for both manufacturers and drivers.
Manufacturers are already in the process of improving their SCR
designs, and overwhelmingly drivers are not waiting for SCR-related
warnings or inducements to be triggered before they refill DEF tanks
and otherwise maintain proper operation of SCR systems. Given the
importance of reducing NOX emissions from heavy-duty diesel
engines for attaining and maintaining national air quality standards,
we have developed the following draft revised guidance to reflect
improving capabilities for designing SCR systems to ensure proper
operation.

VII. SCR Adjustable Parameter Design Criteria

This section discusses design criteria for on-highway heavy-duty
diesel vehicles or engines using SCR technology. EPA believes that
vehicles and engines that meet these design criteria would meet the
requirements of the regulations regarding adjustable parameters. EPA
will still review each certification application to ensure that the
regulatory provisions are met. Likewise, in the case of design criteria
that are not fully specified in this guidance, EPA will review the
application to ensure that the engine design meets the regulatory
requirements. EPA may review and revise this guidance as the technology
continues to mature and as EPA receives more information regarding the
use of SCR systems. In addition, manufacturers may present other
designs for EPA consideration. All designs will remain subject to EPA
approval under the existing certification regulations.
As noted above, in determining the adequacy of an engine's means of
inhibiting adjustment of a parameter, EPA considers the likelihood that
settings other than the manufacturer's recommended setting will occur
in use. With this in mind, EPA is providing these draft SCR adjustable
parameter design criteria based on our view that an SCR-equipped
vehicle that complies with these criteria will be adequately inhibited
from use when the SCR system is not operating properly.
EPA is asking for comments on the draft guidance discussed below.
The design criteria are divided into four categories. The categories
are:
A. Reductant tank level driver warning system.

[[Page 32894]]

B. Reductant tank level driver inducement.
C. Identification and correction of incorrect reducing agent.
D. Tamper resistant design.

A. Reductant Tank Level Warning System

The emissions performance of SCR-equipped vehicles depends on
having an adequate supply of appropriate quality reducing agent in the
system. SCR systems require regular user interaction to ensure that the
system is operating properly. Therefore, it is critical that the
operator both know when reducing agent is needed and have enough time
to replace it before it runs out. A properly designed driver warning
system should address these concerns.
To achieve this design goal, under our criteria, the manufacturers
would use a warning system including the following features:
1. The warning system should incorporate visual and possibly
audible alarms informing the vehicle operator that reductant level is
low and must soon be replenished. The manufacturer should design the
warning system to activate well in advance of the reducing agent
running out so that the operator is expected to have one or more
refueling opportunities to refill the reductant tank before it is
empty.
2. The warning alarm(s) should escalate in intensity as the
reducing agent level approaches empty, culminating in driver
notification that is difficult to ignore, and cannot be turned off
without replenishment of the reducing agent.
3. To provide adequate notice, the visual alarm should, at a
minimum, consist of a DEF level indicator, a unique light, reducing
agent indicator symbol or message indicating low reducing agent level.
The warning light, symbol or message should be different from the
``check engine'' or ``service engine soon'' lights used by the On Board
Diagnostic (OBD) system or other indicators that maintenance is
required. The symbol or message used as the warning indicator should
unmistakably indicate to the vehicle operator that the reducing agent
level is low. The reducing agent indicator symbol shown below has been
generally accepted in the industry and EPA considers it acceptable as
an indicator of low reducing agent level.
[GRAPHIC] [TIFF OMITTED] TP07JN11.008

4. The light, indicator symbol or message should be located on the
dashboard or in a vehicle message center. The warning light or message
does not initially have to be continuously activated, but as the
reducing agent level approaches empty the illumination of the light or
message would escalate, culminating with the light being continuously
illuminated or the message continuously broadcast in the message
center. Many current designs have been found acceptable and EPA does
not anticipate requiring changes in the foreseeable future. Unique SCR
system warning lights and message designs that deviate from previously
approved designs or the design criteria outlined above would need to be
approved by EPA.
Manufacturers may also incorporate an audible component of the low
DEF warning system. As the reducing agent level approaches empty the
audible warning system should escalate.

B. Low Reductant Level Inducement

The warning systems discussed above can play a critical role in
achieving vehicle compliance. As noted, a well designed warning system
should deter drivers from operating SCR-equipped vehicles without
reducing agent. However, we believe an additional, stronger deterrent
is necessary and appropriate. Therefore, at some point after the
operator receives the initial signal warning that reductant level is
low, it is important that the engine design incorporates measures to
induce users to replenish the reducing agent.
Under these design criteria, manufacturers would design their
engines with a final inducement system that accomplishes the following
when the reductant tank is empty or the SCR system is incapable of
proper dosing:
1. Maximum vehicle speed is decreased at the quickest safe rate to
5 miles per hour while the vehicle is operating; or
2. The maximum engine fueling and engine speed are decreased at the
quickest safe rate while the vehicle is operating, resulting in engine
shutdown or limiting operation capability to idle only.
Some manufacturers prefer to trigger the above final inducement
only when the vehicle has stopped at a safe location. Under this
approach, a vehicle may be assumed to be in a safe location if the
engine is purposefully shut off (key turned to the off position), has
experienced an extended idle of 60 minutes (as indicated by zero
vehicle speed for 60 minutes), or a refueling event has occurred
(meaning a volume of fuel has been added equal to or greater than 15
percent of vehicle operating fuel capacity).
If a manufacturer chooses to implement final inducement only when
the vehicle is stopped, we believe the engine will need to be designed
with the following additional characteristics:
a. Be able to trigger final inducement when the vehicle is stopped
at a safe location. The final inducement will consist of limiting the
vehicle speed to 5 mph, shutting the engine down, or limiting engine
operation to idle only.
b. Prior to triggering final inducement, be able to impose a severe
inducement which makes prolonged operation of the vehicle unacceptable
to the driver and compels the driver to replenish the reducing agent
prior to the SCR system becoming incapable of proper dosing. The severe
inducement will consist of an engine derate, a vehicle speed
limitation, or a limitation on the number of engine restarts. For
example, an engine torque derate of 40 percent may be utilized as a
severe inducement for the operator of a Class 8 line-haul truck to
replenish the reducing agent. The severe inducement should occur while
there is enough reductant in the tank to continue to provide proper SCR
dosing for approximately one full day of vehicle operation. For
example, it may be appropriate to initiate severe inducement with a 10
percent reserve of reducing agent in the reductant tank.
c. Be able to determine when the vehicle has arrived at a safe
location for the purpose of imposing a final inducement. Such a
determination will be based upon the vehicle experiencing the next key-
off, refueling, or 60-minute idling event after imposing severe
inducement. During the course of one day of vehicle operation, EPA
believes it sufficiently likely an operator will encounter one of the
three events triggering final inducement. In the unlikely scenario that
one of the three events is not encountered, the severe inducement
should still provide sufficient incentive for the operator to refill
the reductant tank.
The above final and severe inducements are not meant to limit the
use of other inducements prior to severe or final inducement. EPA
encourages the use of additional inducements which would serve to
minimize the amount of time either severe or final inducements are
encountered.
When developing inducement strategies for review by EPA at the time
of certification, manufacturers should be prepared to detail the type
and level of inducements chosen and demonstrate how they will
sufficiently compel drivers to maintain appropriate reductant levels
and ensure vehicle operation is limited only to periods when proper SCR
dosing is occurring.

[[Page 32895]]

EPA believes that an engine that is designed with warning and
inducement strategies consistent with those above will be highly
unlikely to be driven with an empty reductant tank, and therefore that
such an engine would be adequately protected from operation with an
empty tank.

C. Identification and Correction of Incorrect Reducing Agent

Assuring that an SCR-equipped engine is unlikely to be operated
without proper reducing agent calls for an SCR system design that is
able to detect incorrect or poor quality reducing agent. As noted above
in the context of maintaining an adequate level of reducing agent, the
emissions performance of SCR-equipped vehicles is dependent on having
reducing agent in the system and the reducing agent must be of the
proper quality. Therefore, the system must be able to identify and
appropriately respond to poor reductant quality such as filling the
reductant storage tank with a fluid other than the manufacturer-
specified reducing agent, or with excessively diluted reducing agent.
An example would be filling the tank with water rather than DEF, when
DEF is the specified reducing agent.
Current urea-based SCR technology uses a robust NOX
sensor system to detect poor quality reductant. High NOX
emissions can be correlated to poor reductant quality and
NOX sensors are already part of the SCR system. Urea quality
sensors directly measure DEF quality and appear likely to represent a
quick detection method for addressing quality concerns in the future.
Manufacturers are currently evaluating the performance and durability
of various sensor designs.
NOX sensor systems will take somewhat longer to detect
poor quality reducing agent compared to urea quality sensors. Under
ideal conditions, NOX sensors can detect poor quality in 20
minutes, but may take as long as one hour to detect poor quality
reductant. An advantage of urea quality sensors is that, once fully
developed, they will provide operator notification of poor quality
while the vehicle is still at a filling location.
Because NOX sensors do not directly measure DEF quality,
they do not detect variations in DEF quality as small as those detected
by urea quality sensors. However, NOX sensors adequately
detect water which is the most likely substitute for DEF. Therefore,
NOX sensors are likely able to detect and prevent the
majority of serious quality problems. Because of the ability of urea
quality sensors to detect smaller concentration deviations in urea
quality, we believe urea quality sensors will soon be the best
reasonable technology to help manufacturers meet the adjustable
parameter requirement. Urea quality sensors will also permit the
emission control system to adjust DEF dosing based on the detected
quality of the DEF and, in conjunction with the inducement strategies,
help ensure that only compliant DEF is used. We expect urea quality
sensors to be available for use in 2013 model year vehicles.
Under these design criteria, the engine design would have the
following features to identify and respond appropriately to poor
quality reducing agent or incorrect fluid:
1. Given the current technology, we believe manufacturers should be
capable of detecting poor reductant quality within one hour. As
improved technology becomes available, such as urea quality sensors,
manufactures should decrease the likelihood, and increase the
performance consequences of operation with poor quality reductant by
incorporating the technology which best and most promptly detects poor
reductant quality.
2. Immediately upon detection, the operator should be notified of
the problem with warnings similar to those discussed above for
inadequate reductant level. EPA expects the warning light or message
addressing incorrect reducing agent would quickly increase in intensity
to be continuously activated.
3. Given the current state of technology, the engine design should
implement final inducement while the vehicle is operating and within 4
hours of detection. Alternately, if a manufacturer chooses to implement
final inducement when the vehicle is stopped at a safe location, the
engine design should implement severe inducement and search for final
inducement triggers within 4 hours of detection. For this alternate
approach, some lesser inducement should precede severe inducement at 2
hours after detection. While we believe it is appropriate that the
vehicle respond in a similar manner when poor quality reducing agent is
detected as when the vehicle runs low on reducing agent, we believe the
inducement should not begin immediately. It is currently possible for a
driver to receive poor quality reductant unknowingly and for a driver
to need a certain amount of time after being alerted to the problem to
have it remedied. Therefore, we think it currently appropriate to allow
no more than 4 hours of operation following detection before imposing
severe or final inducement. The 4 hours until severe or final
inducement will allow the operator sufficient time to reach a service
facility to remedy the problem.
4. If poor quality reductant is detected again within 40 hours
after putting proper reducing agent in the tank, then the operator
should be immediately notified and the poor quality final inducement or
the alternate severe inducement approach should begin immediately. We
believe continuing to monitor for repeat instances of poor quality
reductant for 40 hours is likely to capture the vast majority of
operators intentionally trying to circumvent SCR controls.
EPA believes design requirements that alert the operator to
inadequate reducing agent and that institute inducements to assure
correction of reducing agent quality are needed in order to ensure that
the ``adjustable parameter'' of reductant quality is sufficiently
limited. EPA believes that the warnings and inducements associated with
poor quality reducing agent discussed above are burdensome enough that
they ensure that introduction of poor quality reductant would not occur
often or purposely and that in the unlikely event it occurs, proper
actions will be taken within reasonable time limits to adequately
minimize the operation of the vehicle/engine with poor quality
reductant and associated excess emissions. We also believe the 4 hours
until severe or final inducement is currently needed to allow the
operator to locate and drive to a service facility capable of draining
and refilling the tank.
EPA believes that an engine that is designed with the warning and
inducement strategies discussed above will be highly unlikely to be
driven with inadequate reductant for any significant period, and
therefore that such an engine would be adequately protected from
operation with inadequate reductant.

D. Tamper Resistant Design

SCR systems should be designed to be tamper resistant to reduce the
likelihood that the SCR system will be circumvented or that the
operating parameters of the system will be purposefully or
inadvertently altered. Manufacturers should be careful to review any
element of design that would prevent the proper operation of the SCR
system to make tampering with that element of design impossible or
highly unlikely. Manufacturers will have to demonstrate to EPA that
their SCR system design is tamper resistant. 40 CFR 86.094-22(e)
contains provisions regarding actions and criteria to ensure that
elements of design related

[[Page 32896]]

to the adjustable parameters of DEF level and quality are adequately
inaccessible, sealed, physically limited or stopped, or otherwise
inhibited from adjustment.
1. At a minimum, the following actions, if done intentionally,
would be considered tampering and manufacturers should design their SCR
systems to ensure that restraints on such actions, whether purposeful
or not, are adequate and such results are unlikely:

a. Disconnected reductant level sensor
b. Blocked reductant line or dosing valve
c. Disconnected reductant dosing valve
d. Disconnected reductant pump
e. Disconnected SCR wiring harness
f. Disconnected NOX sensor (that is incorporated with the
SCR system)
g. Disconnected reductant quality sensor
h. Disconnected exhaust temperature sensor
i. Disconnected reductant temperature sensor

2. EPA believes that the warnings and inducements described above
for incorrect reducing agent would also be adequate under 40 CFR Sec.
86.094-22(e) to prevent tampering or accidental actions causing the
above results. The engine should be able to detect tampering as soon as
possible, but no longer than one hour after a tampering event.
3. Immediately upon detection, the operator should be notified of
the problem.
4. We believe the inducement should not begin immediately. It is
possible that a part failure that occurs in the course of normal
operation will be recognized as a result of these diagnostics. An
operator should not immediately receive inducement for an event which
may not have been caused by tampering. Therefore, we think it
appropriate to allow 4 hours of operation following detection before
implementing final inducement while the vehicle is in operation.
Alternately, if a manufacturer chooses to implement final inducement
when the vehicle is stopped at a safe location, the engine design
should implement severe inducement and search for final inducement
triggers within 4 hours of detection. For this alternate approach, some
lesser inducement should precede severe inducement at 2 hours after
detection. The 4 hours until severe or final inducement will allow the
operator sufficient time to reach a service facility to remedy the
problem.
5. If tampering of the same component is detected again within 40
hours after repair, then the operator should be immediately notified
and the tampering final inducement, or the alternate severe inducement
approach, should begin immediately. We believe continuing to monitor
for repeat instances of tampering for 40 hours is likely to capture the
vast majority of operators intentionally trying to circumvent SCR
controls.
EPA believes that an engine that is designed with the warning and
inducement strategies discussed above will be highly unlikely to be
driven for any significant period under the aforementioned conditions,
and that such an engine would be adequately protected from operation
under such circumstances.

VIII. Conclusion

EPA is releasing this draft document for comments. We will continue
to work with manufacturers, other stakeholders, and the public
regarding issues related to its existing regulatory requirements and
SCR technology.

Dated: May 27, 2011.
Margo Tsirigotis Oge,
Director, Office of Transportation and Air Quality, Office of Air and
Radiation.
[FR Doc. 2011-13851 Filed 6-6-11; 8:45 am]
BILLING CODE 6560-50-P