32886 Federal Register / Vol. 76, No. 109 / Tuesday, June 7, 2011 / Proposed Rules 

§ 31.3402(t)–1 [Corrected] 

On Page 26679, column 2, under the 

paragraph heading § 31.3402(t)–1 

Withholding requirement on certain 

payments made by government entities, 

line 7 from the bottom of the paragraph, 

the language ‘‘a mere renewal of a 

contract. A material’’ is corrected to read 

‘‘a mere renewal of a contract that does 

not otherwise materially affect the 

property or services to be provided 

under the contract, the terms of 

payment for the property or services 

under the contract, or the amount 

payable for the property or services 

under the contract. A material’’. 

LaNita VanDyke, 

Chief, Publications and Regulations Branch, 

Legal Processing Division, Associate Chief 

Counsel (Procedure and Administration). 

[FR Doc. 2011–13928 Filed 6–6–11; 8:45 am] 

BILLING CODE 4830–01–P 

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. 

SUMMARY: EPA is requesting comment 

on draft guidance and related 

interpretations concerning the 

application of certain emission 

certification regulations to those onhighway 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 


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Federal Register / Vol. 76, No. 109 / Tuesday, June 7, 2011 / Proposed Rules 32887 

1A 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. 

2The 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. 

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. 

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. 

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 


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32888 Federal Register / Vol. 76, No. 109 / Tuesday, June 7, 2011 / Proposed Rules 

3This cost is represented in terms of 1978 dollars. 

Adjusting for inflation, this would equate to 

roughly $70.00 in 2011 dollars. 

4U.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. 

5See docket number EPA–HQ–OAR–2010–0444– 

0018. 

6U.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. 

7See 75 FR 39251 (July 8, 2010). 

8See docket number EPA–HQ–OAR–2010–0444– 

0016. The strawman proposal was not final 

guidance. 

9See 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. 

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. 

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. 

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. 

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. 

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 heavyduty diesel engines.7 In particular, EPA 

reviewed approaches to designing SCRequipped 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 heavyduty 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 


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Federal Register / Vol. 76, No. 109 / Tuesday, June 7, 2011 / Proposed Rules 32889 

10California 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. 

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. 

V. Experience to Date 

A. EPA’s Certification Program 

For the 2010 and 2011 model years, 

EPA has certified a total of 71 onhighway 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 thirdparty 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. 

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. Sixtyeight 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 


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32890 Federal Register / Vol. 76, No. 109 / Tuesday, June 7, 2011 / Proposed Rules 

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. 

12See docket number EPA–HQ–OAR–2010– 

0444–0019. 

13When 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. 

14See docket number EPA–HQ–OAR–2010– 

0444–0020. 

15See 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. 

16Section 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. 

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. 

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 SCRequipped 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. 

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. 

D. Cummins Survey 

In 2010, Cummins collected 

information from 47 different customerowned 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: 

• 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 SCRequipped 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 manufacturerdesigned inducements, which is in 

contravention to EPA tampering 

regulations.16


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17See docket number EPA–HQ–OAR–2010– 

0444–0021. 

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. 

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. Onisland 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 industrywide 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 


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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. 

19Such actions are illegal, unless conducted as 

part of a testing program covered by an Agencyissued testing exemption. 

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 heavyduty 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. 

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 SCRequipped 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. 

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 uphill. 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 


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20See 40 CFR Part 85, Subpart T. 

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. 

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 inuse 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 SCRrelated 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. 


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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 SCRequipped 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. 

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. 


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Federal Register / Vol. 76, No. 109 / Tuesday, June 7, 2011 / Proposed Rules 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 


emcdonald on DSK2BSOYB1PROD with PROPOSALS
32896 Federal Register / Vol. 76, No. 109 / Tuesday, June 7, 2011 / Proposed Rules 

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 § 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 

DEPARTMENT OF HOMELAND 

SECURITY 

Federal Emergency Management 

Agency 

44 CFR Part 67 

[Docket ID FEMA–2011–0002; Internal 

Agency Docket No. FEMA–B–1194] 

Proposed Flood Elevation 

Determinations 

AGENCY: Federal Emergency 

Management Agency, DHS. 

ACTION: Proposed rule. 

SUMMARY: Comments are requested on 

the proposed Base (1% annual-chance) 

Flood Elevations (BFEs) and proposed 

BFE modifications for the communities 

listed in the table below. The purpose 

of this proposed rule is to seek general 

information and comment regarding the 

proposed regulatory flood elevations for 

the reach described by the downstream 

and upstream locations in the table 

below. The BFEs and modified BFEs are 

a part of the floodplain management 

measures that the community is 

required either to adopt or to show 

evidence of having in effect in order to 

qualify or remain qualified for 

participation in the National Flood 

Insurance Program (NFIP). In addition, 

these elevations, once finalized, will be 

used by insurance agents and others to 

calculate appropriate flood insurance 

premium rates for new buildings and 

the contents in those buildings. 

DATES: Comments are to be submitted 

on or before September 6, 2011. 

ADDRESSES: The corresponding 

preliminary Flood Insurance Rate Map 

(FIRM) for the proposed BFEs for each 

community is available for inspection at 

the community’s map repository. The 

respective addresses are listed in the 

table below. 

You may submit comments, identified 

by Docket No. FEMA–B–1194, to Luis 

Rodriguez, Chief, Engineering 

Management Branch, Federal Insurance 

and Mitigation Administration, Federal 

Emergency Management Agency, 500 C 

Street, SW., Washington, DC 20472, 

(202) 646–4064, or (e-mail) 

luis.rodriguez1@dhs.gov. 

FOR FURTHER INFORMATION CONTACT: Luis 

Rodriguez, Chief, Engineering 

Management Branch, Federal Insurance 

and Mitigation Administration, Federal 

Emergency Management Agency, 500 C 

Street, SW., Washington, DC 20472, 

(202) 646–4064, or (e-mail) 

luis.rodriguez1@dhs.gov. 

SUPPLEMENTARY INFORMATION: The 

Federal Emergency Management Agency 

(FEMA) proposes to make 

determinations of BFEs and modified 

BFEs for each community listed below, 

in accordance with section 110 of the 

Flood Disaster Protection Act of 1973, 

42 U.S.C. 4104, and 44 CFR 67.4(a). 

These proposed BFEs and modified 

BFEs, together with the floodplain 

management criteria required by 44 CFR 

60.3, are the minimum that are required. 

They should not be construed to mean 

that the community must change any 

existing ordinances that are more 

stringent in their floodplain 

management requirements. The 

community may at any time enact 

stricter requirements of its own or 

pursuant to policies established by other 

Federal, State, or regional entities. 

These proposed elevations are used to 

meet the floodplain management 

requirements of the NFIP and also are 

used to calculate the appropriate flood 

insurance premium rates for new 

buildings built after these elevations are 

made final, and for the contents in those 

buildings. 

Comments on any aspect of the Flood 

Insurance Study and FIRM, other than 

the proposed BFEs, will be considered. 

A letter acknowledging receipt of any 

comments will not be sent. 

National Environmental Policy Act. 

This proposed rule is categorically 


emcdonald on DSK2BSOYB1PROD with PROPOSALS