The Administrator of the Environmental Protection Agency, Lisa Jackson, signed the following rule on May 23, 

2012 and EPA is submitting it for publication in the Federal Register. While we have taken steps to ensure the 

accuracy of this Internet version of the rule, it is not the official version. Please refer to the official version in a 

forthcoming Federal Register publication, which will appear on the Government Printing Office’s FDSys website 

(http://fdsys.gpo.gov/fdsys/search/home.action) and on Regulations.gov (http://www.regulations.gov) in Docket No. 

EPA-HQ-OAR-2011-1032. Once the official version of this rule is published in the Federal Register, this version 

will be removed from the Internet and replaced with a link to the official version.

6560-50-P 

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 85, 86 and 1039 

[EPA-HQ-OAR-2011–1032; FRL–9673-1] 

RIN A2060-AR54

Heavy-Duty Highway Program: Revisions for Emergency Vehicles

AGENCY: Environmental Protection Agency (EPA). 

ACTION: Direct Final Rule. 

SUMMARY: EPA is taking direct final action on revisions to its heavy-duty diesel regulations 

that will enable emergency vehicles, such as dedicated ambulances and fire trucks, to perform 

mission-critical life-saving work without risking that abnormal conditions of the emission 

control system could lead to decreased engine power, speed or torque. The revisions will allow 

manufacturers to request and EPA to approve modifications to emission control systems on 

emergency vehicles so they do not interfere with the vehicles’ missions. This action is not 

expected to result in any significant changes in regulatory burdens or costs. 

DATES: This rule is effective on [Insert date 60 days from date of publication in the 

Federal Register] without further notice, unless EPA receives adverse comment. If we receive 

relevant adverse comment on distinct elements of this rule by July 27, 2012, we will publish a 

timely withdrawal in the Federal Register indicating which provisions we are withdrawing. The 

provisions that are not withdrawn will become effective on [Insert date 60 days from date of 

publication in the Federal Register], notwithstanding adverse comment on any other provision. 

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-OAR-2011-

1032, by one of the following methods: 

• www.regulations.gov: Follow the on-line instructions for submitting comments.

• Email: a-and-r-docket@epa.gov

• Fax: (202) 566-9744 

• Mail: Environmental Protection Agency, Air Docket, Mail-code 6102T, 1200 Pennsylvania 

Ave., NW, Washington, DC 20460. 

• Hand Delivery: EPA Docket Center (EPA/DC), EPA West, Room 3334, 1301 Constitution 

Ave., NW., Washington, DC, Attention Docket No. EPA-HQ- OAR-2010-0162. 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-2011-1032. For additional 

instructions on submitting written comments, see the SUPPLEMENTARY INFORMATION 
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Lisa Jackson, on May 23, 2012. We have taken steps to ensure the accuracy of this version, but it is not the official 

version.

Page 2 of 41

section on “Public Participation” in the parallel Notice of Proposed Rulemaking in today’s 

Federal Register. 

Docket: All documents in the docket are listed in the 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 www.regulations.gov or in hard copy at EPA Docket Center, 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: Lauren Steele, Environmental Protection 

Agency, Office of Transportation and Air Quality, Assessment and Standards Division, 2000 

Traverwood Drive, Ann Arbor, Michigan 48105; telephone number: 734-214-4788; fax number: 

734-214-4816; email address: steele.lauren (@epa.gov). 

SUPPLEMENTARY INFORMATION

Why is EPA Using a Direct Final Rule?

EPA is publishing this rule without a prior proposed rule because we view this as a 

noncontroversial action and anticipate no adverse comment. This is also to expedite the 

regulatory process to allow engine and vehicle modifications to occur as soon as possible.

However, in the “Proposed Rules” section of today’s Federal Register, we are publishing a 

separate document that will serve as the proposed rule to adopt these revisions for emergency 

vehicles if adverse comments are received on this direct final rule. We will not institute a second 

comment period on this action. Any parties interested in commenting must do so at this time. 

For further information about commenting on this rule, see the ADDRESSES section of this 

document. 

If EPA receives adverse comment on a distinct provision of this rulemaking, we will publish a 

timely withdrawal in the Federal Register indicating which provisions we are withdrawing. The 

provisions that are not withdrawn will become effective on the date set out above, 

notwithstanding adverse comment on any other provision. We would address all public 

comments in a subsequent final rule based on the proposed rule. 

EPA is publishing this direct final rule to expedite the deployment of solutions that will best 

ensure the readiness of the nation’s emergency vehicles. We request that commenters identify in 

your comments any portions of the action with which you agree and support as written, in 

addition to any comments regarding suggestions for improvement or provisions with which you 

disagree. In the case of a comment that is otherwise unclear whether it is adverse, EPA would 

interpret relevant comments calling for more flexibility or less restrictions for emergency 

vehicles as supportive of the direct final action. In this way, the EPA will be able to adopt those 

elements of this action that are fully supported and most needed today, while considering and 
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Lisa Jackson, on May 23, 2012. We have taken steps to ensure the accuracy of this version, but it is not the official 

version.

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addressing any adverse comments received on the proposed rule, in the course of developing the 

final rule.

Does This Action Apply to Me?

This action may affect you if you produce or import new heavy-duty or nonroad diesel engines 

that are intended for use in vehicles that serve the emergency response industry, including all 

types of dedicated and purpose-built fire trucks and ambulances. The following table gives some 

examples of entities that may be affected by this action. Because these are only examples, you 

should carefully examine the existing and revised regulations in 40 CFR parts 85, 86 and 1039. 

If you have questions regarding how or whether these rules apply to you, you may call the person 

listed in the FOR FURTHER INFORMATION CONTACT section above.

Category NAICS Codea Examples of Potentially Affected Entities

Industry 336111 Motor Vehicle Manufacturers, Engine and 

336112 Truck Manufacturers

333618

336120

Industry 541514 Commercial Importers of Vehicles and 

811112 Vehicle Components 

811198

Industry 811310 Engine Repair, Remanufacture, and 

Maintenance

Note: a

 North American Industry Classification System (NAICS)

Table of Contents 

I. Overview

II. Statutory Authority and Regulatory Background

A. Statutory Authority

B. Background: 2007 and 2010 NOX and PM Standards

(1) On-Highway Standards

(2) Nonroad Standards

III. Emergency Vehicle Provisions

A. Background on Regulation of Emergency Vehicles

B. Why is EPA Taking This Action?

(1) How Does a DPF Work?

(2) Why Are Emergency Vehicles Having Problems with DPF Regeneration?

(3) What Are the Concerns for Emergency Vehicles Using SCR?

C. What Would Occur if EPA Took No Action?

(1) The Industry Would Continue to Get Smarter
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Lisa Jackson, on May 23, 2012. We have taken steps to ensure the accuracy of this version, but it is not the official 

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(2) The Fleet Would Continue to Migrate to the 2010 Standards

(3) Some Trucks Would Continue to Experience Problems

D. Regulatory Action

(1) Liberalized Regeneration Requests

(2) Engine Recalibration

(3) Backpressure Relief

E. What Engines and Vehicles Are Affected?

(1) Newly Certified Engines

(2) Certified Engines and Vehicles In-Use

(3) Labeling Requirements

(4) Other Regulatory Provisions

F. Economic Impacts

(1) Costs to Manufacturers

(2) Operational Costs

(3) Societal Costs

G. Environmental Impacts

H. Health Effects

IV. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review

B. Paperwork Reduction Act

C. Regulatory Flexibility Act

D. Unfunded Mandates Reform Act

E. Executive Order 13132: Federalism

F. Executive Order 13175: Consultation and Coordination with Indian Tribal Governments

G. Executive Order 13045: Protection of Children from Environmental Health and Safety Risks

H. Executive Order 13211: Actions that Significantly Affect Energy Supply, Distribution, or Use

I. National Technology Transfer Advancement Act

J. Executive Order 12898: Federal Actions to Address Environmental Justice in Minority 

Populations and Low-Income Populations

K. Congressional Review Act

I. Overview 

EPA is adopting amendments to its heavy-duty diesel engine programs that will 

specifically allow engine manufacturers to request to deploy specific emission controls or 

settings for new and in-use engines that are sold for use only in emergency vehicles. EPA is 

adopting these revisions to enable fire trucks and ambulances with heavy-duty diesel engines to 

perform mission-critical life- and property-saving work without risk of losing power, speed or 

torque due to abnormal conditions of the emission control systems. 

EPA’s current diesel engine requirements have spurred application of emission controls 

systems such as diesel particulate filters (commonly called soot filters or DPF’s) and other aftertreatment systems on most new diesel vehicles, including emergency vehicles. Some control 
This document is a prepublication version, signed by the Administrator of the Environmental Protection Agency, 

Lisa Jackson, on May 23, 2012. We have taken steps to ensure the accuracy of this version, but it is not the official 

version.

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system designs and implementation strategies are more effective in other segments of the fleet 

than in emergency vehicles, especially given some emergency vehicles’ extreme duty cycles. By 

this action, EPA intends to help our nation’s emergency vehicles perform their missions; to 

better ensure public safety and welfare and the protection of lives and property. 

II. Statutory Authority and Regulatory Background

A. Statutory Authority

Section 202(a)(1) of the Clean Air Act (CAA or the Act) directs EPA to establish 

standards regulating the emission of any air pollutant from any class or classes of new motor 

vehicles or new motor vehicle engines that, in the Administrator’s judgment, causes or 

contributes to air pollution which may reasonably be anticipated to endanger public health or 

welfare. Such standards apply for the useful life of the vehicles or engines. Section 202(a)(3) 

requires that EPA set standards applicable to emissions of hydrocarbons, carbon monoxide, NOX

and particulate matter (PM) from heavy-duty trucks that reflect the greatest degree of emission 

reduction achievable through the application of technology which we determine will be available 

for the model year to which the standards apply. We are to give appropriate consideration to 

cost, energy, and safety factors associated with the application of such technology. We may 

revise such technology-based standards, taking costs into account, on the basis of information 

concerning the effects of air pollution from heavy-duty vehicles or engines and other sources of 

mobile source related pollutants on the public health and welfare. 

Section 202(a)(4)(A) of the Act requires the Administrator to consider risks to public 

health, welfare or safety in determining whether an emission control device, system or element 

of design shall be used in a new motor vehicle or new motor vehicle engine. Under section 

202(a)(4)(B), the Administrator shall consider available methods for reducing risk to public 

health, welfare or safety associated with use of such device, system or element of design, as well 

as the availability of other devices, systems or elements of design which may be used to conform 

to requirements prescribed by (this subchapter) without causing or contributing to such 

unreasonable risk. 

Section 206(a) of the Act requires EPA to test, or require to be tested in such manner as it 

deems appropriate, motor vehicles or motor vehicle engines submitted by a manufacturer to 

determine whether such vehicle or engine conforms to the regulations promulgated under section 

202. Section 206(d) provides that EPA shall by regulation establish methods and procedures for 

making tests under section 206. 

Section 213 of the Act gives EPA the authority to establish emissions standards for 

nonroad engines and vehicles (42 U.S.C. 7547). Sections 213(a)(3) and (a)(4) authorize the 

Administrator to set standards and require EPA to give appropriate consideration to cost, lead 

time, noise, energy, and safety factors associated with the application of technology. Section 

213(a)(4) authorizes the Administrator to establish standards to control emissions of pollutants 

(other than those covered by section 213(a)(3)) which “may reasonably be anticipated to 

endanger public health and welfare.” Section 213(d) requires the standards under section 213 to 
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Lisa Jackson, on May 23, 2012. We have taken steps to ensure the accuracy of this version, but it is not the official 

version.

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be subject to sections 206-209 of the Act and to be enforced in the same manner as standards 

prescribed under section 202 of the Act. 

B. Background: 2007 and 2010 NOX and PM Standards

(1) On-Highway Standards 

On January 18, 2001, EPA published a rule promulgating more stringent standards for 

NOX and PM for heavy-duty highway engines (“the heavy-duty highway rule”).1 The 0.20 gram 

per brake-horsepower-hour (g/bhp-hr) NOX standard in the heavy-duty highway rule first applied 

in MY 2007. However, because of phase-in flexibility provisions adopted in that rule and use of 

emission credits generated by manufacturers for early compliance, manufacturers were able to 

continue to produce engines with NOX emissions greater than 0.20 g/bhp-hr. The phase-in 

provisions ended after MY 2009 so that the 0.20 g/bhp-hr NOX standard was fully phased-in for 

model year 2010. Because of these changes that occurred in MY 2010, the 0.20 g/bhp-hr NOX

emission standard is often referred to as the 2010 NOX emission standard, even though it applied 

to engines as early as MY 2007. 

The heavy-duty highway rule adopted in 2001 also included a PM emissions standard for 

new heavy-duty diesel engines of 0.01 g/bhp-hr, effective for engines beginning with MY 2007. 

Due to the flexible nature of the phase-in schedule described above, manufacturers have had the 

opportunity to produce engines that met the PM standard while emitting higher levels of NOX. 

During the phase-in years, manufacturers of diesel engines generally produced engines that were 

tuned so the combustion process inherently emitted lower engine-out NOX while relying on PM 

after-treatment to meet the PM standard. The principles of combustion chemistry dictate that 

conditions yielding lower engine-out NOX emissions generally result in higher engine-out PM 

emissions. This is what we call the NOX-PM trade-off. For many new low-NOX diesel engines 

today, engine-out PM emissions could be at or above the levels seen with the MY 2004 standards 

(0.1 g/bhp-hr). To meet today’s stringent PM standards, manufacturers rely on diesel particulate 

filter after-treatment to clean the exhaust. 

(2) Nonroad Standards

EPA adopted similar technology-forcing standards for nonroad diesel engines on June 29, 

2004.2

 These are known as the Tier 4 standards. This program includes requirements that will 

generally involve the use of NOX after-treatment for engines above 75 hp and PM after-treatment 

(likely soot filters) for engines above 25 hp. These standards phase in during the 2011 to 2015 

time frame. 

 

1 Control of Air Pollution from New Motor Vehicles: Heavy-Duty Engine and Vehicle Standards and Highway 

Diesel Fuel Sulfur Control Requirements (66 FR 5001). 2 Control of Emissions of Air Pollution from Nonroad Diesel Engines and Fuel (69 FR 38958).
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Lisa Jackson, on May 23, 2012. We have taken steps to ensure the accuracy of this version, but it is not the official 

version.

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III. Emergency Vehicle Provisions

A. Background on Regulation of Emergency Vehicles

Typically, the engines powering our nation’s emergency vehicles belong to the same 

certified engine families as engines that are installed in similarly sized vehicles sold for other 

public and private uses.3

 Historically, engine and vehicle manufacturers have sought EPA 

certification for broad engine families and vehicle test groups that are defined by similar 

emissions and performance characteristics. Engine families typically only consider the type of 

vehicle in which the engine is intended to be installed to the extent that it fits into a broad vehicle 

weight class and, to a lesser extent, the vehicle’s intended duty cycle (i.e. urban or highway). 

Because of the above-described manufacturing practices and the narrow CAA authority 

for any exemptions, EPA has historically regulated engines for emergency vehicles, including 

ambulances as well as police vehicles and fire-fighting apparatus, in the same manner as other 

engines. 

In the public comments received on the proposed heavy-duty highway rule, EPA received 

some comments about DPF technologies and regeneration cycles on heavy-duty trucks, including 

one comment that expressed concerns that the systems may not be failsafe.4 However, none of 

the comments specifically raised technical feasibility with respect to emergency vehicles, and 

EPA’s response was based on the best information available at the time. After publishing the 

final rule requiring heavy-duty highway engines to meet performance standards that compelled 

technologies such as DPF’s, EPA received a letter from the National Association of State Fire 

Marshals, requesting some provision for public safety in implementing this new rule, considering 

that fire departments across the nation have trouble covering basic costs and may not have funds 

for more expensive trucks.5 This letter did not raise any technical feasibility issues, and EPA did 

not see a need to take action. 

More recently EPA has received letters from fire apparatus manufacturers and ambulance 

companies requesting relief from power or speed inducements related to low levels of DEF for 

SCR systems on emergency vehicles.

6

 Power and speed reduction inducements were new on 

vehicles equipped with SCR. These were not specifically mandated by EPA but designed by 

 

3 In this rule, emergency vehicle is defined as a fire truck or an ambulance for on-highway applications, and for 

nonroad applications, we are defining emergency equipment as specialized vehicles to perform aircraft rescue and 

firefighting functions at airports, or wildland fire apparatus. See Section III.C and revisions at 40 CFR 86.1803-01 

and 40 CFR 1039.801.

4 Heavy-Duty Highway Final Rule, December 21, 2000, Response to Comments, Section 3.2.1, “Technical

Feasibility of Engine/Vehicle Standards//Diesel Engine Exhaust Standards,” page 3-58 to 3-60, available at 

http://www.epa.gov/otaq/highway-diesel/regs/2007-heavy-duty-highway.htm. 5 Letter dated February 1, 2001 to C. Whitman, EPA Administrator from G. Miller, President, National Association 

of State Fire Marshalls

6 See, for example, letter dated October 22, 2009, from Roger Lackore of the Fire Apparatus Manufacturers’ 

Association and Randy Hanson of the Ambulance Manufacturers Division, to Keisha Jennings of EPA. 
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Lisa Jackson, on May 23, 2012. We have taken steps to ensure the accuracy of this version, but it is not the official 

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manufacturers to occur if DEF levels became low, to induce operators of the vehicles to perform 

the required emission-related maintenance in use. More discussion on this, including why the 

emergency response community requested relief and what action EPA took, is found below in 

Section III.B(3). 

Recently, beginning in October 2011, EPA received a series of comment letters from fire 

chiefs and other interested stakeholders, requesting regulatory action to relieve emergency 

vehicles from the burden of complying with the 2007 PM standards.7

 EPA promptly opened a 

dialogue with the fire chiefs and engine manufacturers to understand the issues. Power and speed 

reductions were occurring on some vehicles with soot filters but without SCR systems, in part 

related to engine protection measures designed by manufacturers. Essentially, these soot filters 

are supposed to be self-cleaning by periodically burning off accumulated soot during normal 

vehicle use. The cleaning process is called regeneration, and when this doesn’t work as 

designed, the filter gradually gets more clogged, which can lead to engine problems. EPA has 

determined that while other pathways are available for resolving some issues related to soot 

filters on emergency vehicles, there remains a public safety issue related to design of engines and 

emission control systems on emergency vehicles that should be addressed through this 

rulemaking. More discussion of this, including why relief was requested and what other actions 

can be taken in addition to EPA regulation, is found below in Sections III.B and III.C. 

There have been some examples of EPA providing limited exemptions for other types of 

emergency-use engines and vessels. Further descriptions of current and proposed limited 

exemptions are provided in the Notice of Proposed Rulemaking published elsewhere in today’s 

Federal Register. These limited exemption provisions are only applicable to newly certified 

engines. They are not applicable to any existing in-use engines that are already deployed in 

emergency equipment.

B. Why is EPA Taking This Action?

EPA is amending its regulations to facilitate engine manufacturers’ design and 

implementation of reliable and robust emission control systems with regeneration strategies and 

other features that do not interfere with the mission of emergency vehicles. Through the 

comments and letters we have received, as well as our own outreach and data-gathering efforts, 

we have learned that some emission control systems on fire trucks and ambulances today, in 

particular, certain applications using diesel particulate filters, are requiring an unexpected 

amount of operator interventions, and there are currently a nontrivial number of emergency 

vehicles that are electronically programmed to cut power or speed – even while responding to an 

emergency - when certain operational parameters are exceeded in relation to the emission control 

system. As we understand it, the experiences of operators are mixed, with some not reporting 

any problems and some reporting problems that raise public safety and welfare concerns. 

 

7 See, for example, letter dated October 4, 2011 from Congressman Filner to EPA Administrator Jackson, and letter 

dated October 14, 2011, from Director Cimini of the Southeast Association of Fire Chiefs to EPA Administrator 

Jackson.
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EPA’s standards are performance-based, and reflect the greatest degree of emission 

reduction achievable, according to CAA sections 202(a)(3) and 213(a)(3). Our on-highway and 

nonroad PM standards do not specify the type of diesel particulate filter for manufacturers to use, 

nor do they even mandate the use of such a filter. Our analysis of the feasibility of the 2007 onhighway PM standard is presented in Chapter III of the final Regulatory Impact Analysis (RIA)

for that rule.8

 Our analysis of the feasibility of the Tier 4 nonroad compression ignition engine 

standards that will be phasing in through 2015 is presented in Chapter 4 of that rule’s final RIA.9 

For most nonroad engines, these standards are similar in stringency to the 2007 on-highway 

heavy-duty engine and vehicle standards. As described below in Section III.H, these two rules 

are providing billions of dollars of annual health benefits by virtually eliminating harmful PM 

emissions from the regulated engines. Even so, EPA is required by sections 202(a)(4)(B) and 

213(c) of the Act to, among other things, consider methods for reducing risk to public safety and 

welfare associated with the use of emission control devices or systems. 

Based on the information available to us, we have concluded that there is an indirect risk 

to public safety and welfare associated with some examples of emission control systems when 

they are deployed on emergency vehicles that experience extreme duty cycles. This indirect risk 

is related to the readiness of emergency vehicles and the risk that they may not be able to 

respond during emergencies with the full power, torque, or speed that the engine is designed to 

provide. While this risk is not inherent to the requirement to reduce emissions or to the use of 

diesel particulate filters on emergency vehicles, EPA believes it is appropriate to ensure that 

emergency vehicles can perform their emergency missions without the chance of such 

consequences. 

EPA’s current rules already provide the opportunity for manufacturers to address many 

issues through applications for certification of new engines and new vehicles. There is also 

currently a mechanism for manufacturers to deploy field modifications to the in-use fleet, 

including those that are substantially similar to approved upgrades for new vehicles, as well as 

those that apply only to vehicles that are no longer in production. As manufacturers become 

aware of the need for upgrades or enhancements, this process occurs within the new and in-use 

fleet with various degrees of application. While that process is occurring today, EPA views this 

issue as serious enough that we would be remiss if we did not act to ensure that our regulations 

clearly offer the needed flexibilities for emergency vehicles.

(1) How Does a DPF Work? 

To explain more fully the issues that we are addressing with this action, and hence why 

we are taking this action, we are providing here some background information on diesel 

particulate filters and the process of DPF regeneration. DPF’s are exhaust after-treatment 

 

8 Final Regulatory Impact Analysis for the “2007 Heavy-Duty Highway Rule,” EPA420-R-00-026, December 2000. 

Chapter III, Emissions Standards Feasibility, is available at http://www.epa.gov/otaq/highway-diesel/regs/ria-iii.pdf 9 Final Regulatory Impact Analysis for “Control of Emissions from Nonroad Diesel Engines,” EPA420-R-04-007, 

May 2004. Chapter 4, Technologies and Test Procedures for Low-Emission Engines, is available 

http://www.epa.gov/nonroad-diesel/2004fr/420r04007e.pdf
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Lisa Jackson, on May 23, 2012. We have taken steps to ensure the accuracy of this version, but it is not the official 

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devices that significantly reduce emissions from diesel-fueled vehicles and equipment. DPF’s

physically trap PM and remove it from the exhaust stream. Figure III-1 depicts a schematic of a 

wall-flow monolith style filter, with the black arrows indicating exhaust gas laden with particles, 

and the gray arrows indicating filtered exhaust gas. This style of filter is the most common in 

today’s heavy-duty diesel engines, and has very high rates of filtration, in excess of 95 percent.10 

Figure III-1 Illustration of air flow pattern in a wall-flow monolith style PM filter (Source: Corning)

To be successful, these devices generally must be able to accomplish two things: collect 

PM and clean away accumulated PM. There are two main types of PM that can accumulate: 

combustible and non-combustible, and two very different types of cleaning methods: 

regeneration and ash cleaning. Regeneration occurs relatively frequently, and is designed to 

complete the combustion (oxidation) of the trapped combustible PM components, releasing them 

to the exhaust as gas-phase compounds (mostly H2O and CO2). In contrast to the PM that can be 

oxidized and carried out the tailpipe as gases, the non-combustible PM such as metallic ash 

cannot be destroyed through regeneration and will always remain inside a DPF. To clean ash 

from a DPF, the filter unit is removed from the vehicle and professionally cleaned with a special 

machine. Fortunately, there is very little ash formation from modern diesels so ash cleaning and 

ash disposal occurs very infrequently, generally with at least 150,000 mile service intervals, and 

the mass of accumulated ash is generally small (a few teaspoons).11,12 This distinction is made 

 

10 See Final RIA Chapter III, Note 8, above. 11 EPA’s regulations at 40 CFR 86.004-25(b)(4) for heavy-duty diesel engine maintenance specify a minimum 

interval for DPF ash cleanout from 100,000 to 150,000 mi. Many manufacturers design DPF systems with longer 

maintenance intervals.

12 See http://www.arb.ca.gov/diesel/tru/documents/ashguide.pdf
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Lisa Jackson, on May 23, 2012. We have taken steps to ensure the accuracy of this version, but it is not the official 

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here because the ash cleaning process is not a source of concern that has given rise to this EPA 

action. The infrequent cleaning of noncombustible materials from DPF’s is not part of the scope 

of this action. 

 Regeneration, however, is a type of routine DPF cleaning that must occur regularly, and 

for which EPA does not specify a minimum interval in its regulations, in contrast to the ash 

cleaning process. At its very essence, regeneration involves burning off the accumulated soot. 

Since this burning can involve extra heat and/or oxygen or oxygen-containing compounds, this 

must be done carefully and safely to avoid uncontrolled burns. The discussion below in Section 

III.B.(1)(b) describes the three types of routine DPF regeneration: passive regeneration, 

automatic active regeneration, and manual (parked) active regeneration. Additional discussion is 

provided in the accompanying Notice of Proposed Rulemaking published elsewhere in today’s 

Federal Register and in a memorandum to the docket.13 Below, we discuss the reason why 

regeneration is needed at all. 

(a) Failure of a DPF 

When the style of filter installed on a diesel vehicle is the wall-flow type that is 

predominant in the market today, it physically traps so much of the PM that the particles 

accumulate on the inside of the filter and if not burned off, this PM can over time block the 

passages through the filtering media, making it more restrictive to exhaust flow. This is 

commonly referred to as “trap plugging.” Some other styles of filter, such as flow-through 

DPF’s, are less prone to plugging, but do not generally reduce the PM emission rate sufficiently 

to meet today’s stringent PM standard. Any time something gets in the way of free flowing air 

through an engine, it creates what we call “exhaust backpressure.” Even a clean, new DPF 

generates a small amount of exhaust backpressure due to the porous walls through which all of 

the exhaust flows. 

Engines can tolerate a certain range of exhaust backpressure. When an increase in this 

backpressure, or resistance, is detected, engines can compensate to a point. An increase in

exhaust backpressure from a DPF trapping more and more PM represents increased work 

demanded from the engine to force the exhaust gas through the increasingly restrictive DPF. 

However, unless the DPF is frequently cleansed of the trapped PM, this increased work demand

can lead to reductions in engine performance and increases in fuel consumption. This loss in 

performance may be noticed by the vehicle operator in terms of poor acceleration and generally 

poor drivability of the vehicle. 

If a DPF is not regenerated and it becomes plugged, there is a risk of two types of failure. 

The degree of this risk and which consequence may be experienced will depend on the engine 

and emission control system design. One consequence is that the lack of air flowing through an 

engine will cause an engine to shut down because it can no longer compensate for the extra work 

being demanded of it. The other is a risk of catastrophic DPF failure when excessive amounts of 

 

13 See memo dated May 4, 2012, “Diesel Particulate Filter Regeneration,” Docket ID EPA-HQ-OAR-2011-1032. 
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Lisa Jackson, on May 23, 2012. We have taken steps to ensure the accuracy of this version, but it is not the official 

version.

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trapped PM begin to oxidize at high temperatures (i.e., DPF regeneration temperatures above 

1,000°C) leading to a “runaway” combustion of the PM within the DPF. This can cause 

temperatures in the filter media to increase beyond its physical tolerance, possibly creating high 

thermal stresses where the DPF materials could crack or melt. This is an unsafe condition, 

presenting physical danger to occupants as well as to objects and persons near the vehicle. 

Further, catastrophic failure can allow significant amounts of the diesel PM to pass through the 

DPF without being captured. That is, the DPF is destroyed and PM emission control is lost. For 

all these reasons, most manufacturers generally design their emission control systems to prevent 

uncontrolled shutdown or runaway DPF regeneration by programming the engine’s electronic 

control module (ECM) to limit maximum engine speed, torque and/or power when excessive 

backpressures are detected. This mode of engine operation at reduced performance may allow a 

vehicle to “limp home” to receive service. In extreme cases the ECM may command the engine 

to shut down to prevent a catastrophic failure.

(b) Types of Regeneration 

There are three types of routine DPF regeneration. Passive regeneration refers to methods 

that rely strictly on the temperatures and constituents normally available in the vehicle’s exhaust 

to oxidize PM from a DPF in a given vehicle application. Passive regeneration is an automatic 

process that occurs without the intervention of an engine’s on-board diagnostic and control 

systems, and often without any operator notice or knowledge. Passive regeneration is often a 

continuous process, because of which, it is sometimes referred to as continuous regeneration. In 

a vehicle whose normal operation does not generate temperatures needed for passive DPF 

regeneration, the system needs a little help to clean itself. This process is called active 

regeneration, and supplemental heat inputs to the exhaust are provided to initiate soot oxidation. 

There are two types of active regeneration: those that may occur automatically either while the 

vehicle is in motion, while idling, or while powering an auxiliary device such as a pump or 

ladder (power take-off (PTO) mode)), and those that must be driver-initiated and occur only 

while the vehicle is stationary and out-of-service. 

Vehicles with automatic active regeneration systems require operators to be alert to 

dashboard lamps and indicators. Written instructions are provided to operators to explain what 

each lamp means (such as high temperatures or need for regeneration) and what action is called 

for (such as driving at highway speeds or initiating a manual active regeneration). Because EPA 

emissions standards are performance based; and therefore, do not dictate any required emission 

control system technologies or configurations, each manufacturer has the discretion to program 

the timing and sequence of lamps as needed to inform drivers of the condition of the emission 

control system. As noted above, it is not uncommon in today’s heavy-duty fleet for an engine’s 

ECM to limit its maximum speed, torque or power when a plugging DPF is detected. These 

engine and emission control system protection measures can alert drivers to the need to change 

driving conditions to facilitate automatic active regeneration or to make plans to allow for a 

manual active regeneration.

A manual active regeneration allows the engine’s ECM to increase engine speed and 

exhaust temperature to a greater extent than what is typically allowed during an automatic active 

regeneration. Because the ECM takes full control of an engine during a manual active 
This document is a prepublication version, signed by the Administrator of the Environmental Protection Agency, 

Lisa Jackson, on May 23, 2012. We have taken steps to ensure the accuracy of this version, but it is not the official 

version.

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regeneration, the vehicle must remain parked and not used for other purposes, such as pumping 

water in PTO mode. Some manual active regenerations may require towing the vehicle to a 

special service center, and may occur while the DPF is on the vehicle, or offline with the DPF 

removed from the vehicle. In such cases, if a spare DPF is not available, the vehicle could be out 

of service overnight. If a driver disregards such warnings, the risk of uncontrolled engine 

shutdown or a catastrophic DPF failure may increase. EPA encourages the design of robust 

systems calling for minimal driver interventions, while providing drivers with clear and early 

indicators before any interventions are needed. EPA also encourages accurate and thorough 

operator training to ensure that the correct remedial action is taken at the earliest available time.

Actively regenerating DPF systems typically require sufficient air flow, temperature and 

soot accumulation before an automatic active regeneration will be requested by the engine’s 

ECM. As mentioned above, this may occur either while the vehicle is in motion or parked, if 

pre-set engine operating conditions are met (such as speed and temperature). When the engine’s 

ECM signals the initiation of an automatic active regeneration and the extra heat is generated, an 

ideal DPF system accomplishes this as a transparent process, with no effects perceivable by the

driver.

A variety of manufacturer approaches can be taken to produce the supplemental heat 

needed for active regeneration. Diesel engines of MY 2007 or newer often incorporate one or 

more of the following approaches: 

• On-board electrical heaters upstream of the filter. 

• Air-intake throttling in one or more of the engine cylinders. When necessary, this device 

would limit the amount of air entering the engine, raising the exhaust temperature and 

facilitating regeneration. 

• Exhaust brake activation. When necessary, this device would limit the amount of exhaust 

exiting the engine, raising the exhaust temperature and facilitating regeneration. 

• Engine speed increases. This approach is sometimes used in combination with the other 

approaches to deliver more heat to the filter to facilitate regeneration.

• Post top-dead-center (TDC) fuel injection. Injecting small amounts of fuel in the cylinders of 

a diesel engine after pistons have reached TDC introduces a small amount of unburned fuel 

in the engine’s exhaust gases. This unburned fuel can then be oxidized over an oxidation 

catalyst upstream of the filter or oxidized over a catalyzed particulate filter to combust 

accumulated particulate matter. 

• Post injection of diesel fuel in the exhaust upstream of an oxidation catalyst and/or catalyzed 

particulate filter. This method serves to generate heat used to combust accumulated 

particulates by oxidizing fuel across a catalyst present on the filter or on an oxidation catalyst 

upstream of the filter

• On-board fuel burners upstream of the filter 14

 

14 MECA Diesel Particulate Filter Maintenance: Current Practices and Experience (June 2005) 

http://www.meca.org/galleries/default-file/Filter_Maintenance_White_Paper_605_final.pdf 
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Lisa Jackson, on May 23, 2012. We have taken steps to ensure the accuracy of this version, but it is not the official 

version.

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These are presented here merely as examples, and are by no means a complete list of the 

strategies available to manufacturers when designing engines that use automatic active DPF 

regeneration, though not all may be applicable to all engines. A common approach that gets a lot 

of consumer attention is the use of fuel burners or fuel injection strategies. This approach is 

often called “dosing.” Vehicle owners may notice an increase in fuel consumption when driving 

a vehicle that relies heavily on fuel dosing for its automatic active regenerations. In this case, 

when an engine’s ECM gives the signal, the doser injects a metered amount of diesel fuel into 

the exhaust flow (or cylinders), which reacts with the DPF catalyst to raise the temperature to a 

point that enables regeneration. EPA does not have information about which manufacturers 

employ this technique or the number or types of vehicles with engines that use fuel dosing as 

part of the active regeneration strategy. Estimates of the additional fuel use by a vehicle whose 

DPF regeneration system employs fuel dosing are described in the Notice of Proposed 

Rulemaking published elsewhere in today’s Federal Register. This is also mentioned here 

because one of the possible outcomes of this EPA action is that some manufacturers may alter 

their strategies for automatic active regenerations on emergency vehicles, which may have a 

modest effect on supplemental fuel use due to dosing. 

(2) Why Are Emergency Vehicles Having Problems with DPF Regeneration?

At the time of promulgation of the heavy-duty highway rule, EPA and the engine 

manufacturers expected the 2007-compliant engine emission control systems would be integrated 

with advanced engine controls to ensure DPF regeneration under all vehicle operating conditions 

and environments. While this is widely true today, the experience of the rule implementation 

thus far indicates there are still some exceptions.

Although EPA is aware of a relatively small number of emergency vehicles that are 

experiencing problems with DPF regeneration, of those that are having problems, most of the 

problems can be related to the vehicle’s duty cycle, the ambient conditions, and/or the engine’s 

combustion characteristics. A vehicle’s duty cycle means how it is driven, including its speeds, 

loads, and distances, as well as time out of service and time spent idling. A vehicle’s duty cycle 

can vary by the demographic of the service area, including whether the vehicle responds to 

emergencies in a rural or urban community, and whether it drives over flat or hilly terrain. 

Because DPF regeneration requires heat and oxygen (basic ingredients for combustion), the 

success of DPF regeneration strategies can also be influenced by ambient conditions such as 

extreme cold winter temperatures and whether the vehicle operates near sea level or at a high 

elevation. The engine combustion and exhaust characteristics can influence the success of a DPF 

regeneration strategy since parameters such as engine-out NOX and PM emission levels can 

influence how easily the soot can be oxidized, and how much soot needs to be oxidized and how 

often. 

Both the engine’s duty cycle and the overall control strategy of the engine’s emission 

control system play a large role in the success of integrating a DPF with an engine to control PM 

emissions. In this section we provide additional discussion of how engine combustion 

characteristics and vehicle duty cycle can lead to DPF regeneration problems on emergency 

vehicles. In Section III.D, below, we discuss our regulatory action to address these issues. 

While our approach specifically targets engine combustion characteristics and emission control 
This document is a prepublication version, signed by the Administrator of the Environmental Protection Agency, 

Lisa Jackson, on May 23, 2012. We have taken steps to ensure the accuracy of this version, but it is not the official 

version.

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system design, we encourage emergency vehicle owners to inquire with their dealers and 

manufacturers regarding suitable vehicle and engine options that are appropriate for their duty 

cycle as well as their demographic and geographic location.

(a) Engine Combustion Characteristics 

Engine combustion characteristics can be designed to enable continuous passive 

regeneration or to rely heavily on automatic active regeneration. As mentioned above, 

regeneration is a combustion process, burning off the accumulated PM or soot. The PM is 

created because the initial combustion process in the engine was imperfect. To completely 

convert all fuel to CO2 and water, the combustion process needs more heat and oxygen. Both of 

these things create NOX because nitrogen (N2) is naturally present in the air and readily oxidizes 

at high temperatures. Thus there is a NOX-PM trade-off of most diesel combustion processes 

(homogeneous charge compression ignition being an exception) where lower combustion 

temperatures help control NOX but create more PM, and higher temperatures that destroy PM (or

prevent it from being created) can generate more NOX. 

In an engine with a DPF system, combustion settings, or calibrations that enable 

continuous passive regeneration, tend to be those with higher engine-out NOX and lower engineout PM, partly because of the higher temperatures that create the NOX, partly because of the 

NOX itself that can act as an oxidizer (to burn off soot), and partly because of the lighter soot 

loading rate. In contrast, engine calibrations that may lead to a heavy reliance on automatic 

active regeneration tend to be those with lower engine-out NOX and higher engine-out PM, partly 

because of the lower temperatures, partly because of a lack of helpful NOX, and partly because of 

a heavier soot loading rate. Note that “engine-out” means emissions upstream of any aftertreatment cleaning devices such as DPF or SCR. An example of a DPF system that may rely 

almost exclusively on active regeneration to maintain a clean PM filter, from an engine 

calibration perspective, would be an engine using advanced exhaust gas recirculation, because it 

would have very low engine-out NOX and relatively high engine-out PM. An example of a DPF 

system that may rarely experience automatic active regeneration (and frequently passively 

regenerate), from an engine calibration perspective, would be an engine using SCR to control 

NOX, because it could have comparatively high engine-out NOX and relatively low engine-out 

PM. The SCR after-treatment would then reduce the high engine-out NOX to provide very low 

tailpipe NOX. 

Thus it is important to note that this NOX-PM trade-off is a critical design parameter 

when developing an engine that will be successfully integrated with a DPF-equipped emission 

control system. To date, all of the concerns expressed to EPA regarding emergency vehicles 

with DPF regeneration issues have been for vehicles that do not employ SCR technology, and 

thus may have higher engine-out PM. The differences in engine combustion characteristics of 

the MY 2007 vehicles compared to those of the majority of MY 2010+ vehicles support the 

concept that the emergency vehicle fleet may experience fewer DPF regeneration troubles as it 

migrates to engines that use after-treatment to meet EPA’s 2010 NOX standards. Such a trend 

may indicate that some engine manufacturers may see a greater need to address in-use 

emergency vehicles than new vehicles. 
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(b) Duty Cycles

As noted above, the duty cycle of a vehicle is one of the factors that influences how often 

the DPF regenerates passively or actively. It is important to note that all DPF systems with 

active regeneration components also have the capability to passively oxidize soot accumulated 

on the filter, though some of the above-described factors may inhibit successful passive 

regeneration. Operation at highway speeds and high engine loads (high load means demanding 

more work from the engine, such as accelerating, driving uphill or carrying heavy cargo) 

typically leads to successful passive regeneration of a DPF. An example from a duty-cycle 

perspective of a vehicle that frequently experiences automatic passive regeneration would be a 

long-haul tractor-trailer. There is also often a threshold of speed or load that is required for 

automatic active regeneration strategies as well, though not as great as for passive regeneration – 

often at least 5 miles/hour or parked with a PTO engaged. In some vehicles, passive 

regeneration occurs so rarely that a DPF system relies almost exclusively on active regenerations 

to maintain a clean PM filter. An example of this from a duty-cycle perspective would be a 

vehicle that operates at idle, low speed and low load over most of its duty cycle. Many 

emergency vehicles fall into this category.

A detailed discussion of the duty cycles of emergency vehicles is provided in the Notice 

of Proposed Rulemaking published elsewhere in Today’s Federal Register. The data provided in 

that discussion indicate that engines on emergency vehicles across the country are commonly 

operated over duty cycles that offer very limited opportunities to regenerate DPF’s. It is also 

important to note that emergency vehicles do not typically get deployed on planned duty 

schedules with predictable blocks of garage time for servicing or maintenance. While some 

other types of vocational vehicles may have duty cycles with many characteristics similar to 

those shown above, emergency vehicles are unique in their need to be ready to deploy at any 

moment for the purpose of protecting public safety and welfare by saving human lives that may 

be in immediate danger.

When trucks with an engine-driven PTO are working in a stationary PTO mode, some 

engines achieve the conditions to enable an automatic active regeneration during this time. 

While this is normally designed to be a transparent process, in practice some effects of this type 

of regeneration have been noticed by operators. EPA has received information from fire chiefs 

indicating that there have been instances where engine ECM’s took control from the operator 

during water pumping operations. When an automatic active regeneration is initiated during a 

water pumping operation, for example, an ECM may be programmed to alter throttle position or 

engine speed to achieve the conditions needed to complete an automatic active regeneration. 

Depending on the design of the water pumping system’s pressure regulation, this may in turn 

affect the water pressure in the fire hoses. EPA has not heard of this occurring on a widespread 

basis, and has reason to believe that affected engine and truck manufacturers have identified and 

corrected this issue on some vehicles. EPA’s current regulations already allow manufacturers to 

develop and request EPA approval for certification of engines with emission control strategies 

where the process of undergoing automatic active regeneration would not interfere with safely 

pumping fire suppressant. 
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While not addressed directly in this action, there are technologies that could be 

implemented to decrease the amount of time emergency vehicles spend with their main engines 

operating at light loads and at idle. These technologies include electronically programmed 

automatic engine start/stop systems and hybrids. Automatic start/stop systems automatically 

stop and start an engine depending upon whether or not it is needed to supply power to the 

vehicle. This technology is already being implemented on other heavy-duty vehicles to decrease 

unnecessary engine idling. Hybrid drivetrains also decrease engine idling with an integrated 

alternate power source such as a battery. We are currently seeing an increase in the use of hybrid 

technologies in heavy-duty diesel vocational vehicles. Garbage trucks, utility company trucks, 

and other work trucks are using hybrid technology to power on-board hydraulic systems and cab 

heating and cooling systems. In conventional vehicles these systems are powered by a main 

engine typically operating at light load or at idle. Because automatic start/stop and hybrid 

technologies improve fuel economy and decrease greenhouse gas emissions, we believe that they 

will be used in more and more vehicles in the future. We believe there is potential for these 

technologies to be integrated into future designs of emergency vehicles to decrease their 

operation at light loads and at idle. Such technologies would not only improve fuel economy and 

decrease greenhouse gas emissions from emergency vehicles, they would also help to prevent 

their diesel particulate filters from becoming plugged due to excessive operation at light loads 

and at idle. While we are not taking any specific action at this time related to decreasing the 

amount of time emergency vehicles operate at light load or at idle, in the accompanying NPRM, 

we request comment on the potential for application of alternate power sources and idle 

reduction technologies on emergency vehicles.

(3) What Are the Concerns for Emergency Vehicles Using SCR?

Selective Catalytic Reduction (SCR) is an exhaust after-treatment system used to control 

NOX emissions from heavy-duty engines by converting NOX into nitrogen (N2) and water (H2O). 

The technology depends on the use of a catalytic converter and a chemical reducing agent, which 

generally is in an aqueous urea solution, and is often referred to as diesel exhaust fluid (DEF). 

Some trade names for this chemical reductant include AdBlue, BlueDef, NOxBlue, and 

TerraCair.

Most engine manufacturers chose to comply with the 2010 NOX emission standard by 

adding SCR to their engine models. In general, the approach with an SCR system has been a 

sound and cost effective pathway to comply with EPA’s 2010 emissions standards, and it is the 

primary path being used today. 

DEF is injected into the exhaust upstream of the SCR catalyst where it forms ammonia 

and carbon dioxide. The ammonia then reacts with NO and NO2, so that one molecule of urea 

can reduce two molecules of NO or one molecule of NO2. A robust SCR system can achieve 

about 90 percent reduction in cycle-weighted NOX emissions. Improvements have been made 

over the last several years to improve the NOX conversion rate and reduce the impact of lower 

exhaust temperatures on the conversion efficiency. 

Because an SCR system is only effective when DEF is injected into the exhaust, we 

consider refilling a vehicle’s DEF tank to be a critical emission-related engine maintenance 

requirement. We are proposing to take action to establish this in our regulations, as described in 
This document is a prepublication version, signed by the Administrator of the Environmental Protection Agency, 

Lisa Jackson, on May 23, 2012. We have taken steps to ensure the accuracy of this version, but it is not the official 

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Section V of the Notice of Proposed Rulemaking published elsewhere in today’s Federal 

Register. Therefore, manufacturers have implemented a number of strategies to induce a vehicle 

operator to refill a vehicle’s DEF tank when needed. These operator inducements generally 

include first illuminating one or more dashboard lights to warn the operator that the DEF tank 

needs to be refilled soon. However, if such initial inducements are persistently ignored by the 

vehicle operator, eventually additional inducements are typically activated that decrease the 

maximum speed or power of the vehicle. These additional inducements are intended to create 

conditions making operational conditions of the vehicle increasingly unacceptable if the initial 

dashboard lamp illumination inducements are persistently ignored. Similar inducements may 

occur in cases where DEF quality does not meet system specifications, or if the SCR system is 

not functioning correctly for another reason. 

While decreasing vehicle performance can be an effective inducement strategy, we 

believe it may not be appropriate in all situations for emergency vehicles because of their special 

need to be ready at any moment for the purpose of protecting public safety and welfare by saving 

human lives that may be in immediate danger. We recognized this during the initial 

implementation of our 2010 NOX standards, and we worked with the Fire Apparatus 

Manufacturers’ Association (FAMA), the Ambulance Manufacturers Division of the National 

Truck Equipment Manufacturers Association, and the International Association of Fire Chiefs to 

support the publication of a May 18, 2010 memo that instructed emergency vehicle 

manufacturers and engine manufacturers to implement less severe inducement strategies for 

emergency vehicles.15 In this rule we are taking additional steps so that emergency vehicle 

manufacturers and engine manufacturers have the option to further reduce the severity or 

eliminate altogether any performance related inducements that are or could be implemented on 

emergency vehicles and their engines during emergency situations. We believe that this 

additional flexibility will help to prevent any abnormal condition of a vehicle’s emission control 

system from adversely affecting the speed, torque, or power of an emergency vehicle during 

emergency situations.

C. What Would Occur if EPA Took No Action?

(1) The Industry Would Continue to Get Smarter

Improving the components of diesel particulate filters is the current subject of research 

and development activities within the automotive and air pollution control industries. Aspects 

that are being improved include filter ash storage capacity, filter pressure drop, substrate 

durability, catalyst activity, as well as other physical and chemical properties that can optimize 

the device for heavy-duty vehicle applications. 

Engine manufacturers have taken a systems approach, optimizing the engine with its 

after-treatment system to realize the best overall performance possible. Manufacturers can 

 

15 FAMA 2010, Emergency Vehicle SCR and DEF Inducement Guidelines; 2010 Engine Emissions Control 

Requirements
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version.

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manage the functioning of the emission control system by adjusting parameters such as the 

thermal profile of the after-treatment system, the exhaust gas chemical composition, the rate of 

consumption of DEF, the rate of particle deposition, and the conditions under which DPF 

regenerations (soot cleaning) may occur. 

In a broad and general sense, the trend is that DPF’s are slowly becoming even more 

robust without EPA intervention. Future DPF’s will need fewer total regenerations during the 

useful life of the engine and control system, more passive and fewer active regenerations will 

occur, and manual regenerations will become rarer. 

In addition, vehicle operators and fleet managers will continue to become more 

experienced with this new generation of sophisticated electronically-controlled vehicles. 

Manufacturers across the country are providing training on actions fleet managers can take to 

decrease problems with DPF regenerations. These actions include: 

• Use low-ash engine oils

• Avoid extended idling 

• Maintain insulation on the exhaust pipe 

• Maintain the crankcase filter

• Periodically operate a vehicle at higher speeds and loads

The Technology & Maintenance Council (TMC) of the American Trucking Associations 

conducted a survey in late 2011 to compare user experiences between EPA 2010, EPA 2007, and 

EPA 2004 vintage trucks. 16 According to TMC, 72 percent of the survey respondents indicated 

that driver understanding of the 2007-vintage after-treatment system was worse than driver 

understanding of the 2004-vintage after-treatment system, and 33 percent of respondents 

indicated that driver understanding of the 2010-vintage after-treatment system was worse than 

driver understanding of the 2007-vintage after-treatment system. The responses regarding driver 

understanding of fault codes and dash lamps indicated that drivers have 69 percent poorer 

understanding of 2007 vs. 2004 fault codes and dash lamps, and 50 percent poorer understanding 

of 2010 vs. 2007 fault codes and dash lamps. We expect that this education component will 

gradually improve over time without EPA intervention. 

(2) The Fleet Would Continue to Migrate to the 2010 Standards 

Vehicles with 2010-compliant heavy-duty diesel engines tend to place different demands 

on their DPF systems than pre-2010 vehicles. With the addition of NOX after-treatment such as 

SCR, engines may be tuned to emit lower engine-out PM (recall the NOX-PM trade-off described 

above). When an SCR system is integrated, it provides the opportunity to run an engine at lower 

 

16 American Trucking Associations, Technology & Maintenance Council, S3 Engine Study Group. Survey

conducted Fall 2011, public slides dated February 2012 available at 

http://www.truckline.com/Federation/Councils/TMC/Documents/2012%20Annual%20Meeting%20and%20Exhibiti

on%20Documents/TMC12A_TECH2.pdf
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Lisa Jackson, on May 23, 2012. We have taken steps to ensure the accuracy of this version, but it is not the official 

version.

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soot levels and elevated levels of NO2, which is a chemical species that efficiently oxidizes the 

soot in the absence of elevated temperatures. It is EPA’s expectation that vehicles of MY 2010 

and beyond, particularly those using SCR, will generally experience fewer troubles with DPF’s 

than the earlier model year vehicles, due to the nature of the on-board technology as well as the 

many years of experience gained by manufacturers since 2007. The 2011 TMC survey included 

an assessment of relative satisfaction levels between EPA 2010, EPA 2007, and EPA 2004 

vintage trucks. The survey results indicate that after-treatment durability is better with EPA 

2010 trucks compared to EPA 2007 trucks, with less time out of service.17 As an illustration, 

according to a Volvo product brochure, the company’s EPA 2010-compliant trucks eliminate the 

need for active DPF regeneration, reducing driver involvement with the emission control system, 

using a design that allows for the DPF system to reliably oxidize accumulated soot using 

continuous passive regeneration.18

(3) Some Trucks Would Continue to Experience Problems

Even though such trends would indicate that instances of emergency vehicles 

experiencing difficulty managing regeneration of DPF’s would decrease, in the absence of this 

EPA action, some vehicles would be likely to continue to experience some problems. 

EPA has learned that some engine manufacturers have disabled these engine protection 

measures on some emergency vehicles. In these cases the manufacturer has reasoned that an 

operator should be allowed to remain in control of an emergency vehicle even facing risk of 

catastrophic failure, with the consequences of that failure being less severe than the 

consequences of the vehicle prematurely losing power, torque and/or speed while performing 

emergency services.

Without a clear action from EPA to provide the regulatory flexibility needed for swift 

deployment of robust remedies throughout the emergency vehicle fleet, implementation of best 

practices could be inconsistent, insufficient, or even impossible due to regulatory constraints. 

Some vehicles would continue to experience frequent plugging of DPF’s, frequent forced filter 

regenerations, and reduced engine power, speed or torque that diminish the ability of first 

responders to save lives and property. There would also remain a heightened risk that an 

emergency vehicle could be taken out of service when it is most needed. 

D. Regulatory Action

As described above in Section III.C, many DPF-equipped vehicles include engine 

controls and driver alerts that lead to decreases in maximum speed, torque, or power when DPF 

backpressure exceeds normal levels, as protective measures for either the engine or the DPF, or 

 

17 See ATA/TMC, Note 16. 18 See Volvo 2010 product brochure, “Volvo’s SCR No Regen Engine,” available at 

http://www.volvotrucks.com/SiteCollectionDocuments/VTNA_Tree/ILF/Products/2010/09-

VTM075_NoRegen_SS_041609.pdf
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Lisa Jackson, on May 23, 2012. We have taken steps to ensure the accuracy of this version, but it is not the official 

version.

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as inducements for the operator to immediately conduct DPF regeneration. Similarly, vehicles 

equipped with selective catalytic reduction (SCR) systems for NOX reduction currently have 

engine controls and driver alerts that lead to eventual loss of speed, torque, or power when the 

SCR controls detect abnormal conditions (such as a malfunction, low DEF levels, etc.), as 

inducements to take immediate corrective action to allow the SCR to function normally. In most 

vehicles, these alerts and inducements may be easily avoided with normal driving and routine 

maintenance, and if activated, these inducements would not have any significant effect on public 

safety and welfare. In emergency vehicles, however, should any of these limits on maximum 

speed, torque, or power occur while a vehicle is responding to an emergency, it could be a matter 

of life or death. To address these issues that could otherwise limit the maximum speed, torque or 

power of an emergency vehicle’s engine when it is needed most, EPA is proposing to amend 40 

CFR part 86 to revise the definition of defeat device; add new definitions of emergency vehicle, 

ambulance and fire truck; and add new labeling requirements for new on-highway engines with 

approved Auxiliary Emission Control Devices for emergency vehicles. EPA is also amending its 

regulations at 40 CFR part 1039 to revise the definition of defeat device, add a new definition of 

emergency equipment, and add a new labeling requirement for nonroad engines with approved 

Auxiliary Emission Control Devices for emergency equipment. 

In our current regulations, engine manufacturers may request as part of an application for 

new engine or vehicle certification, and EPA may approve, Auxiliary Emission Control Devices, 

if they are not determined to be “defeat devices.” Auxiliary Emission Control Devices, or 

AECD’s, are any design element of an engine’s emission control system that senses temperature, 

vehicle speed, engine RPM, transmission gear, manifold vacuum, or any other parameter for the 

purpose of activating, modulating, delaying, or deactivating the operation of any part of the 

emission control system.19 Some AECD’s can temporarily decrease the effectiveness of an 

emission control system. This type of AECD is only permitted in very limited situations, for 

example, when such excursions are deemed to be necessary in order to protect the vehicle, 

engine, and or emission control system during limited modes of operation.

A defeat device is a type of AECD that reduces the effectiveness of vehicle emission 

controls in situations when such reduction in effectiveness is not approved or permitted by EPA. 

Defeat devices are not permitted by the Clean Air Act or EPA. 

Approvals of AECD’s are made by EPA on a case-by-case basis. In applications for 

engine certification, manufacturers must include a detailed description of each AECD to be 

installed in or on any vehicle (or engine) covered by the application, as well as a detailed 

justification of each AECD that results in a reduction in effectiveness of the emission control 

system. According to 40 CFR 86.094-21(b)(1)(i)(B), EPA may disapprove a request for an 

AECD based on consideration of currently available technology. Use of an unauthorized or 

disapproved AECD can be considered a violation of section 203 of the Act.20

 

19 See 40 CFR 86.082-2 20 See 40 CFR 86.094-21 and 094-22
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In this action, EPA is proposing to revise the definition of defeat device at 40 CFR 

86.004-2, 86.1803-01, and 40 CFR 1039.115 to exclude AECD’s that apply only for engines on 

emergency vehicles, where the need for an AECD is justified in terms of preventing the vehicle 

or equipment from losing speed, torque, or power due to abnormal conditions of the emission 

control system, or in terms of preventing such abnormal conditions from occurring during 

operation related to emergency response. 

In this action, EPA is proposing to define an emergency vehicle as a vehicle that is an 

ambulance or a fire truck. EPA is proposing to adopt a definition of ambulance consistent with 

the current U.S. General Services Administration Star of Life specification.21 EPA is proposing 

to define fire truck as a vehicle designed to be used under emergency conditions to transport 

personnel and equipment and to support the suppression of fires and mitigation of other 

hazardous situations, consistent with the scope of standards for automotive fire apparatus issued 

by the National Fire Protection Association.22 We are defining emergency equipment as 

specialized vehicles to perform aircraft rescue and firefighting functions at airports, or wildland 

fire apparatus. With these definitions, it is EPA’s intent to include vehicles that are purpose-built 

and exclusively dedicated to firefighting, emergency/rescue medical transport, and/or performing 

other rescue or emergency personnel or equipment transport functions related to saving lives and 

reducing injuries coincident with fires and other hazardous situations. EPA requests comment on 

whether we should refine or expand our definition of emergency vehicle within the scope of this 

action to include those equipped with heavy-duty diesel engines that serve other civilian rescue, 

law enforcement or emergency response functions. We are especially interested in information 

regarding instances of such vehicles experiencing or risking loss of power, speed or torque due to 

abnormal conditions of the emission control system, and how that may inhibit mission-critical 

life- and property-saving work. 

EPA is also adopting an associated engine labeling requirement so that engines with 

approved emergency vehicle AECD’s will be clearly identified and distinguished from other 

similar engines.

As mentioned above in Section III.B, some engine manufacturers currently specify that

when an engine is sold for installation in an emergency vehicle, some of the default power, 

torque or speed inducements be de-activated or set to alternate, less severe settings. In such 

applications, when the DPF system requests regeneration, the warning lights remain illuminated 

while the vehicle remains in complete control of the driver. In these cases the manufacturer has 

likely reasoned that the consequences of catastrophic failure would be less severe than the 

consequences of the vehicle prematurely losing power, torque and/or speed while performing 

emergency services. EPA has granted related AECD’s in the past.

 

21 U.S. General Services Administration, Federal Specification for the Star-of-Life Ambulance, August 1, 2007, 

http://www.deltaveh.com/f.pdf. 22 See National Fire Protection Association web page. Accessed April 2012 at 

http://www.nfpa.org/catalog/product.asp?title=Code-1901-2009-Automotive-FireApparatus&category%5Fname=&pid=190109&target%5Fpid=190109&src%5Fpid=&link%5Ftype=search&icid=
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However, without the optional flexibilities provided by EPA in this action, manufacturers 

could be prevented from implementing truly failsafe solutions for all affected vehicles. For 

example, while current custom solutions may allow an emergency vehicle to continue pumping 

water or transporting a person to safety, its DPF would continue to accumulate particles and the 

risk of catastrophic failure would increase.

In this action, EPA is adopting amendments so that manufacturers can apply for (and 

EPA can approve) AECD’s that may be justified in terms of preventing the occurrence of 

abnormal conditions of the emission control systems for emergency vehicles or in terms of 

preventing the engines from losing speed, torque, or power due to such abnormal conditions. In 

this context, EPA would consider abnormal conditions to be parameters outside normal ranges 

for proper operation, such as excessive exhaust backpressure from high soot loading on a DPF or 

insufficient DEF for use with an SCR system. 

EPA is encouraging manufacturers to apply for AECD’s that are tailored for engines on 

emergency vehicles, considering the duty cycle information presented in the accompanying 

NPRM, along with any other information needed to design failsafe emission control systems for 

new emergency vehicles. EPA is also encouraging manufacturers to design field modifications 

to address these issues on in-use emergency vehicles, including those whose engines are no 

longer in production. Further discussion of field modifications is provided below in Section 

III.E(2).

To achieve these goals, EPA understands that increased flexibility will be needed because 

EPA’s strict NOX and PM standards present many design constraints. Below we describe some 

solutions that EPA believes it could approve as part of an emergency vehicle AECD or field 

modification, as adopted. EPA is encouraging engine manufacturers to apply for emergency 

vehicle AECD’s and/or field modifications for in-use emergency vehicles for which service 

disruptions related to abnormal conditions of emission control systems may occur or have 

occurred. EPA suggests that such AECD’s or field modifications could include, but are not 

limited to, one or more of the following strategies:

(1) Liberalized Regeneration Requests

It is current practice that most modern diesel engine ECM’s are set to initiate an 

automatic active regeneration only above a designated DPF soot load, and those vehicles 

equipped with manual regeneration switches are set to not allow the option of initiating manual 

active regeneration until an even greater soot load is detected. The reason why manufacturers do 

this is related to certification of engine families and vehicle test groups. If manufacturers can 

limit the frequency of regenerations by design, then they can be assured that average emissions 

will remain below the certified average emission level. Excess regenerations could lead to 

higher average emissions, since some exhaust emissions increase during regeneration. 

Particularly for engines not equipped with SCR systems, NOX emissions can increase by an 

order of magnitude during regeneration, and these temporary increases in emission are accounted 

for in EPA’s certification process. See the accompanying NPRM for more information about the 

emissions impacts of DPF regenerations. In addition, excess regenerations could shorten the 

useful life of the DPF system since high temperatures place stress on filter substrates. 
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EPA believes that emergency vehicle AECD’s that enable more frequent automatic active 

and manual active DPF regenerations, associated with a wider range of soot loads could improve 

the reliability of DPF systems without significantly compromising emissions reductions or 

durability. As explained below Section III.E(4), EPA does not expect this provision to affect 

other aspects of certification. For emergency vehicles with approved AECD’s that involve 

changes in the frequency of regeneration, the resulting increase in NOX emissions will not be 

counted against certification levels for applicable engine families or vehicle test groups. 

Furthermore, emissions certification testing may be conducted with any approved AECD’s for 

emergency vehicle or equipment deactivated. According to EPA’s current engine certification 

data, engines from MYs 2008 and 2011 have an average maximum automatic active regeneration 

frequency near 20 percent, with the typical frequency between three and seven percent. Those 

with frequencies near zero rely almost exclusively on passive regeneration.23 

(2) Engine Recalibration 

As mentioned above, in-cylinder combustion chemistry dictates a NOX-PM trade-off 

where engines calibrated to reduce in-cylinder NOX tend to have higher PM levels. These factors 

lead to higher rates of particle accumulation and lower rates of particle oxidation on filters. EPA 

believes that AECD’s that incorporate engine calibration modifications could enable operation in 

a “low soot mode” with a reduced rate of particle deposition that would lead to more frequent 

and effective passive regenerations. Such calibration modifications could also extend the 

operating time between all types of regenerations, improve active regeneration effectiveness, and 

boost reliability of the DPF systems. On engines with downstream (i.e., SCR) NOX controls, 

SCR control could be modulated such that engine recalibration would not significantly affect 

NOX emissions. On engines without downstream NOX controls, EPA believes that some degree 

of increased NOX emissions during the conditions justified by the AECD would be approvable 

for emergency vehicles. As explained below in Section III.E(4), EPA does not expect this 

provision to affect other aspects of certification. When manufacturers calculate the average NOX

emissions during a test cycle, they incorporate data regarding both the frequency of regeneration 

and the increase in NOX emissions during regeneration. For emergency vehicles with approved 

AECD’s that involve recalibration to alter regeneration frequency or average NOX emissions, the 

resulting increase in NOX emissions will not be counted against certification levels for applicable 

engine families or vehicle test groups. Furthermore, emissions certification testing may be 

conducted with any approved AECD’s for emergency vehicle or equipment deactivated. A 

discussion of the estimated emissions impacts of recalibration is provided in the Notice of 

Proposed Rulemaking published elsewhere in today’s Federal Register.

(3) Backpressure Relief

It is EPA’s objective that all of our clean diesel emissions standards be implemented with 

reliable technologies that require a minimum amount of driver intervention and do not 

 

23 Frequency in percent refers to the fraction of engine test cycles during which an automatic active regeneration 

occurs.
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compromise the utility of vehicles. EPA understands that manufacturers are motivated to seek 

design solutions that are cost effective and easily deployable. However, by focusing solely on 

preventive measures such as those described above, manufacturers may not achieve a completely 

failsafe DPF strategy on all emergency vehicles. EPA anticipates that some vehicles may benefit 

from an additional failsafe measure that relieves engine exhaust backpressure as a last resort to 

prevent loss of engine speed, torque or power. There are products on the market today that could 

be configured to temporarily relieve excessive engine exhaust backpressure when detected, then 

return the system to normal at the instant that backpressure returns to a safe level. Such a device 

may be justified as a failsafe measure, and may be included as part of an overall strategy that 

also includes preventive measures, if justified and properly limited, where excess PM emissions 

would be expected to be emitted only during a small fraction of vehicle operation. That is, the 

vast majority of DPF operating cycles would be expected to have continuous PM emission 

control, while any temporary backpressure relief that reduced PM control or allowed bypass of 

controls would be expected relatively infrequently. 

E. What Engines and Vehicles Are Affected? 

Today’s action applies to new and in-use fire trucks and ambulances, new and in-use 

airport fire apparatus and wildland fire apparatus, and heavy-duty diesel engines on these 

emergency vehicles and equipment.

(1) Newly Certified Engines 

Of those new diesel engines covered by EPA’s current heavy-duty diesel standards, only 

those installed in vehicles or equipment meeting the definition of emergency vehicle or 

emergency equipment will be eligible to obtain an approved AECD of the type discussed above 

in Section III.D. Where a vehicle is chassis-certified and either sold as an incomplete vehicle to 

a truck body manufacturer or built and sold as a complete vehicle, only those sold and built as 

emergency vehicles will be eligible to obtain an approved AECD of the type discussed above. 

(2) Certified Engines and Vehicles In-Use

To address in-use engines and vehicles, EPA plans to allow engine and vehicle 

manufacturers to submit requests for EPA approval of Emergency Vehicle Field Modifications 

(EVFMs) for on-highway emergency vehicles and Emergency Equipment Field Modifications 

(EEFMs) for nonroad emergency equipment. EVFMs and EEFMs will be modifications to

existing hardware and software to be installed on in-use vehicles or equipment to prevent loss of 

speed, torque, or power due to abnormal conditions of emission control systems, or to prevent 

such abnormal conditions from occurring, during vehicle or equipment operation related to 

emergency response. EPA will use an approval process similar to the process that is currently 

utilized to submit modifications to current applications for certification, also known as “running 

changes.” The information submitted by a manufacturer to EPA as part of this request and 

approval process will be similar to the information submitted for emergency vehicle or 

equipment AECD’s. 

 It is important to emphasize that this action will allow only those approved 

modifications to be deployed by manufacturers and their authorized dealers. Modifications made 
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by end users are not generally approvable; rather the tampering prohibitions would generally 

apply to such modifications. 

EPA has identified three types of field modifications that will be permitted for emergency 

vehicles and emergency equipment under the final regulations, based on the extent to which the 

modification is being incorporated into new production vehicles and equipment. The three types 

are: 

• Type A: Any field modification that is a change to a certified vehicle (i.e., a vehicle, 

engine or equipment covered by a certificate of conformity) that is identical in all 

respects to a running change that is approved for incorporation in new vehicles by the 

manufacturer. Where the running change was approved by EPA for implementation only 

in conjunction with certain other running changes, the field modification may be 

considered to be a Type A field modification only if implemented under the same 

constraints. 

• Type B: Any field modification that is not identical in all respects to, but provides for 

essentially the same purpose as, a running change that is being incorporated in new 

vehicles by the manufacturer or that would have been incorporated if the vehicle were 

still in production. A Type B field modification is used when it is not practical to 

incorporate the exact running change in vehicles that have left the assembly line, or when 

the vehicles are no longer in production. 

• Type C: Any field modification that is made selectively only to vehicles which have left 

the assembly line and which would not have been incorporated on the assembly line. For 

example, this would apply when making a field modification to a vehicle that is no longer 

in production where there are no similar vehicles in production. 

The amount of justification needed for the field modification differs depending on which 

type of modification is being requested. 

(3) Labeling Requirements

Because the engines and vehicles eligible for the AECD’s described in this proposal 

belong to broadly certified engine families and test groups, when they are sold for installation in 

an emergency vehicle and equipped with one or more approved emergency vehicle AECD’s, 

they must be labeled as such, to distinguish them from other certified engines. EPA is proposing 

adding a labeling requirement to 40 CFR part 86 subpart A, such that engines with one or more 

approved AECD’s for emergency vehicle applications must be labeled with the statement: “THIS 

ENGINE IS FOR INSTALLATION IN EMERGENCY VEHICLES ONLY.” EPA is also 

proposing adding a labeling requirement to 40 CFR part 86 subpart S, such that vehicles with 

one or more approved AECD’s for emergency vehicles, include the following statement on the 

emission control information label: “THIS VEHICLE HAS A LIMITED EXEMPTION AS AN 

EMERGENCY VEHICLE.” EPA is also adding a labeling requirement to 40 CFR part 1039, 

such that nonroad engines with one or more approved AECD’s for emergency equipment include 

a label with the following statement: “THIS ENGINE IS FOR INSTALLATION IN 

EMERGENCY EQUIPMENT ONLY.”
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EPA requests comment on whether these labeling requirements are satisfactory to ensure 

that engines and vehicles operating with approved emergency AECD’s are permanently 

distinguished from similar certified engines. EPA also requests comment on whether a similar 

label should be required for an in-use emergency vehicle or equipment where a field 

modification is deployed that prevents the engine from losing speed, torque, or power due to any 

occurrences of abnormal conditions of the emission control system, or prevents such abnormal 

conditions from occurring.

(4) Other Regulatory Provisions 

Today’s rule will not alter the tampering prohibition in 40 CFR 1068.101(b)(1). This 

provision describes a general prohibition against anyone from removing or rendering inoperative 

an engine’s emission controls before or after entering into service, where an exception is 

provided in 1068.101(b)(1)(ii) for engine modifications needed to respond to a temporary 

emergency, provided that the engine is restored to proper functioning as soon as possible after 

the emergency has passed. EPA encourages manufacturers to design their emergency vehicle 

AECD’s to be engaged only to the extent necessary to prevent the engine from losing speed, 

torque, or power due to abnormal conditions of the emission control system, or to prevent such 

abnormal conditions from occurring during operation related to emergency response. EPA 

recognizes that there may be cases where an AECD may need to be engaged at times other than 

while actively responding to an emergency, in order to assure that loss of speed, torque or power 

does not occur during operation related to emergency response. EPA also recognizes that some 

AECD’s may involve electronic approaches where the engine’s functions would be modulated 

based on exhaust backpressure or other parameters that are not correlated with any emergency 

situation. EPA may even, in extreme cases, such as at high altitude or with certain older MY 

engines allow engagement of AECD’s at all times, if they are justified as necessary to prevent 

engine from losing speed, torque, or power during operation related to emergency response. 

We are also encouraging manufacturers to design their emission control systems to 

discourage tampering. According to EPA’s tampering prohibition, a vehicle operator who 

abuses or alters an approved AECD may be guilty of tampering. For example, if an AECD 

includes enabling an operator to initiate more frequent manual active regenerations, engine 

manufacturers may choose to prevent the abuse of this function by means such as a daily or 

weekly cap on the number of manual active regenerations, or a minimum soot loading for the 

function to engage. As another example, if an emergency vehicle alerts a driver to an abnormal 

condition of its emission control system by illuminating dash lamps, alarms or other warnings 

that do not limit vehicle performance, it is the operator’s responsibility to take prompt action to 

remedy the problem.24 If an operator disregards such warnings beyond the time needed to 

respond to the emergency, this may be considered tampering. It is important to note that if an 

 

24 Although this action will not affect certification of engine families or test groups, EPA’s regulations do offer 

options to manufacturers who wish to ensure that emission-related maintenance will occur in use, including visible 

signals that are not reset until maintenance occurs. 40 CFR 86.004-25(b)(6)(ii).
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emergency vehicle is not equipped to ever allow an operator to initiate a manual active 

regeneration, this may in practice encourage tampering by the end user. 

Manufacturers of highway and nonroad engines will be required to describe any 

emergency vehicle AECD in an application for certification. In this action, we are not proposing 

any revisions to the information needed to review and approve AECD’s. It is common practice 

for manufacturers, in describing AECD’s, to identify engine parameters such as those that would 

operate differently to preserve adequate engine performance during an emergency, including 

information about how the engine would respond under different in-use operating conditions 

under the various sets of conditions that would otherwise cause the engine to operate at less than 

full performance levels. Other than the requirement for a manufacturer to describe the emergency 

vehicle AECD in its application for certification, we do not expect this provision to be relevant 

for other aspects of certification. For example, emissions certification testing may be conducted 

with any approved AECD’s for emergency vehicle or equipment deactivated. Additionally, 

manufacturers do not need to consider emergency vehicle AECD’s when developing infrequent 

regeneration adjustment factors (IRAFs) or when developing deterioration factors (DFs). Thus, 

manufacturers can include emergency and non-emergency engines and vehicles in the same 

engine families and test groups. Manufacturers may also apply for emergency vehicle AECD’s 

for new, existing, and/or formerly approved emissions certificates. 

F. Economic Impacts

EPA expects the economic effects of this rule to be small, and to potentially have benefits 

that are a natural result of easing constraints.

(1) Costs to Manufacturers

Due to the optional and voluntary nature of this action, there are no direct regulatory 

compliance costs to engine manufacturers. To the extent manufacturers elect to develop and 

deploy upgrades to engines for emergency vehicles, they may voluntarily incur some degree of 

costs associated with the following: 

• Design and testing to determine effectiveness of potential AECDs

• Education & outreach to intermediate vehicle manufacturers and end users 

• Deployment of AECDs onto new and in-use emergency vehicles

• Labeling costs

EPA expects any fixed costs will be small, and any variable costs will apply only to the 

engines sold for installation in emergency vehicles or emergency equipment, which comprise 

less than one percent of the heavy-duty on-road fleet, and an even smaller fraction of the nonroad 

fleet. As per standard practice, manufacturers would be free to set a fair market price for any 

approved AECD they offer, to offset the costs incurred in its development. 

(2) Operational Costs

Depending on the type of AECD or field modification that a manufacturer voluntarily 

elects to deploy, some operational costs could increase and some could decrease.
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When an emergency vehicle is experiencing frequent plugging of its DPF, this increases 

maintenance costs for owners and warranty costs for manufacturers. These costs are expected to 

decrease with this action. Furthermore, EPA believes that the potential for reduced warranty 

costs may help to offset the cost to produce and deploy any optional AECD’s. Similarly, EPA 

believes the potential for reduced maintenance and operational costs may offset the cost to 

owners for obtaining requested AECD’s. 

Where DPF systems employ fuel dosing to enable active automatic regenerations, it is 

uncertain whether liberalizing the parameters for initiating regenerations would affect fuel 

consumption, and whether fuel consumption would increase with an increased number of 

regenerations during a given operating period. To the extent regenerations are enabled with 

other means besides fuel, or demand for regenerations is reduced through recalibration, then any 

potential increase in fuel use from dosing would be mitigated. Further discussion of operational 

costs including costs of fuel dosing is provided in the Notice of Proposed Rulemaking published 

elsewhere in Today’s Federal Register. 

(3) Societal Costs 

Because this rule eases constraints on the development of robust DPF systems, the 

economic impacts can only improve with this action. It is presumed that the benefits to society 

of enabling first responders to act quickly when needed outweigh the costs to society of the 

temporary increase in emissions from this small segment of vehicles.

G. Environmental Impacts

We expect any environmental impacts from this action will be small. By promulgating 

these amendments, it is expected that the emissions from this segment of the heavy-duty fleet 

will not change significantly. 

EPA estimates that on-road emergency vehicles comprise less than one percent of the 

national heavy-duty fleet. According to the International Council on Clean Transportation 

(ICCT), less than one percent of all new heavy-duty truck registrations in 2003 to 2007 were for 

emergency vehicles (includes class 8 fire trucks plus other class 3-8 emergency vehicles).25 On 

average, the ICCT’s data suggest that approximately 5,700 new emergency vehicles are sold in 

the U.S. each year; about 0.8 percent of the 3.4 million new heavy-duty trucks registered 

between 2003 and 2007. The available information indicates that the emergency vehicles 

included in the scope of this rulemaking have lower annual vehicle miles traveled than average 

non-emergency vehicles. Therefore, we conclude that they contribute less than 1% of the annual 

air emissions from the heavy-duty diesel truck fleet. 

 

25 ICCT, May 2009, “Heavy-Duty Vehicle Market Analysis: Vehicle Characteristics & Fuel Use, Manufacturer 

Market Shares.”
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Due to the optional and voluntary nature of this action, it is difficult to estimate its overall 

emissions impact accurately. The amendments offer many options to manufacturers, and the 

emissions impacts will depend on which options and strategies are employed, and for how many 

vehicles. Further discussions of potential NOX and PM emissions impacts and fuel consumption 

from dosing are provided in the Notice of Proposed Rulemaking published elsewhere in Today’s 

Federal Register. 

H. Health Effects 

EPA’s clean diesel standards are already providing substantial benefits to public health

and welfare and the environment through significant reductions in emissions of NOX, PM, 

nonmethane hydrocarbons (NMHC), carbon monoxide, sulfur oxides (SOX), and air toxics. We 

project that by 2030, the on-highway program alone will reduce annual emissions of NOX, 

NMHC, and PM by 2.6 million, 115,000 and 109,000 tons, respectively. These emission 

reductions will prevent 8,300 premature deaths, over 9,500 hospitalizations, and 1.5 million 

work days lost. All told, the monetized benefits of the on-highway rule plus the nonroad diesel 

Tier 4 rule total over $150 billion. A sizeable part of the benefits in the early years of these 

programs has come from large reductions in the amount of direct and secondary PM emitted by 

the existing fleet of heavy-duty engines and vehicles, by requiring the use of the higher quality 

diesel fuel in these vehicles. While this final action may slightly increase some emissions, as 

explained in the previous section, we do not expect that these small increases will significantly 

diminish the health benefits of our stringent clean diesel standards. 

IV. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review 

This action is not a “significant regulatory action” under the terms of Executive Order 

(EO) 12866 (58 FR 51735, October 4, 1993) and is therefore not subject to review under 

Executive Orders 12866 and 13563 (76 FR 3821, January 21, 2011). 

B. Paperwork Reduction Act

This action does not impose any new information collection burden. The regulatory relief 

for emergency vehicles is voluntary and optional, and the revisions for engine and vehicle 

maintenance merely codify existing guidelines. However, the Office of Management and Budget 

(OMB) has previously approved the information collection requirements contained in the 

existing regulations under the provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. 

and has assigned OMB Control Numbers 2060-0104 and 2060-0287. The OMB control numbers 

for EPA’s regulations in 40 CFR are listed in 40 CFR part 9. 

C. Regulatory Flexibility Act

The Regulatory Flexibility Act (RFA) generally requires an agency to prepare a 

regulatory flexibility analysis of any rule subject to notice and comment rulemaking 

requirements under the Administrative Procedure Act or any other statute unless the agency 
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certifies that the rule will not have a significant economic impact on a substantial number of 

small entities. Small entities include small businesses, small organizations, and small 

governmental jurisdictions. 

For purposes of assessing the impacts of this rule on small entities, small entity is defined 

as: (1) a small business primarily engaged in shipbuilding and repairing as defined by NAICS 

code 336611 with 1,000 or fewer employees (based on Small Business Administration size 

standards); (2) a small business that is primarily engaged in freight or passenger transportation 

on the Great Lakes as defined by NAICS codes 483113 and 483114 with 500 or fewer 

employees (based on Small Business Administration size standards); (3) a small business 

primarily engaged in commercial and industrial machinery and equipment repair and 

maintenance as defined by NAICS code 811310 with annual receipts less than $7 million (based 

on Small Business Administration size standards); (4) a small governmental jurisdiction that is a 

government of a city, county, town, school district or special district with a population of less 

than 50,000; and (5) a small organization that is any not-for-profit enterprise which is 

independently owned and operated and is not dominant in its field. 

After considering the economic impacts of today’s rule on small entities, I certify that 

this final rule will not have a significant economic impact on a substantial number of small 

entities. 

In determining whether a rule has a significant economic impact on a substantial number 

of small entities, the impact of concern is any significant adverse economic impact on small 

entities, since the primary purpose of the regulatory flexibility analyses is to identify and address 

regulatory alternatives “which minimize any significant economic impact of the rule on small 

entities.” 5 U.S.C. 603 and 604. Thus, an agency may certify that a rule will not have a 

significant economic impact on a substantial number of small entities if the rule relieves 

regulatory burden, or otherwise has a positive economic effect on all of the small entities subject 

to the rule. 

This rule provides regulatory relief related to emergency vehicles. As such, we anticipate 

no costs and therefore no regulatory burden associated with this rule. We have concluded that 

this rule will not increase regulatory burden for affected small entities. 

D. Unfunded Mandates Reform Act

This action contains no Federal mandates under the provisions of Title II of the Unfunded 

Mandates Reform Act of 1995 (UMRA), 2 U.S.C. 1531-1538 for State, local, or tribal 

governments or the private sector. The action imposes no enforceable duty on any State, local or 

tribal governments or the private sector. This direct final rule offers manufacturers the flexibility 

to choose whether to use optional AECD’s based on their strategies for complying with the 

applicable emissions standards. Therefore, this action is not subject to the requirements of 

sections 202 or 205 of the UMRA. 

This action is also not subject to the requirements of section 203 of UMRA because it 

contains no regulatory requirements that might significantly or uniquely affect small 

governments. 
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E. Executive Order 13132: Federalism

This action does not have federalism implications. It will not have substantial direct 

effects on the States, on the relationship between the national government and the States, or on 

the distribution of power and responsibilities among the various levels of government, as 

specified in Executive Order 13132. This direct final rule applies to manufacturers of heavyduty diesel engines and not to state or local governments. Thus, Executive Order 13132 does not 

apply to this action. 

F. Executive Order 13175: Consultation and Coordination with Indian Tribal 

Governments

This action does not have tribal implications, as specified in Executive Order 13175 (65 

FR 67249, November 9, 2000). This direct final rule will be implemented at the Federal level 

and may result in indirect costs on affected engine manufacturers depending on the extent to 

which they take advantage of the flexibilities offered. Tribal governments will be affected only 

to the extent they purchase and use vehicles with regulated engines. Thus, Executive Order 

13175 does not apply to this action. 

G. Executive Order 13045: Protection of Children from Environmental 

Health and Safety Risks

Executive Order 13045: “Protection of Children from Environmental Health Risks and 

Safety Risks” (62 FR 19885, April 23, 1997) applies to any rule that: (1) is determined to be 

“economically significant” as defined under Executive Order 12866, and (2) concerns an 

environmental health or safety risk that EPA has reason to believe may have a disproportionate 

effect on children. If the regulatory action meets both criteria, the agency must evaluate the 

environmental health or safety effects of the planned rule on children, and explain why the 

planned regulation is preferable to other potentially effective and reasonably feasible alternatives 

considered by the agency.

EPA interprets Executive Order 13045 as applying only to those regulatory actions that 

are based on health or safety risks, such that the analysis required under section 5-501 of the 

Order has the potential to influence the regulation. This direct final rule is not subject to 

Executive Order 13045 because it does not establish an environmental standard intended to 

mitigate health or safety risks, and because it is not economically significant under Executive 

Order 12866. 

H. Executive Order 13211: Actions that Significantly Affect Energy Supply, 

Distribution, or Use

This action is not subject to Executive Order 13211 (66 FR 28355 (May 22, 2001)), 

because it is not a significant regulatory action under Executive Order 12866. 
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I. National Technology Transfer Advancement Act

Section 12(d) of the National Technology Transfer and Advancement Act of 1995 

(“NTTAA”), Public Law No. 104-113, 12(d) (15 U.S.C. 272 note) directs EPA to use voluntary 

consensus standards in its regulatory activities unless to do so would be inconsistent with 

applicable law or otherwise impractical. Voluntary consensus standards are technical standards 

(e.g., materials specifications, test methods, sampling procedures, and business practices) that are 

developed or adopted by voluntary consensus standards bodies. NTTAA directs EPA to provide 

Congress, through OMB, explanations when the Agency decides not to use available and 

applicable voluntary consensus standards. 

This action does not involve technical standards. Therefore, EPA did not consider the use 

of any voluntary consensus standards. 

J. Executive Order 12898: Federal Actions to Address Environmental Justice 

in Minority Populations and Low-Income Populations

Executive Order (EO) 12898 (59 FR 7629 (Feb. 16, 1994)) establishes federal executive 

policy on environmental justice. Its main provision directs federal agencies, to the greatest 

extent practicable and permitted by law, to make environmental justice part of their mission by 

identifying and addressing, as appropriate, disproportionately high and adverse human health or 

environmental effects of their programs, policies, and activities on minority populations and lowincome populations in the United States. 

EPA has determined that this direct final rule will not have disproportionately high and 

adverse human health or environmental effects on minority or low-income populations. This 

action is not expected to have any adverse environmental impacts.

K. Congressional Review Act

The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the Small Business 

Regulatory Enforcement Fairness Act of 1996, generally provides that before a rule may take 

effect, the agency promulgating the rule must submit a rule report, which includes a copy of the 

rule, to each House of the Congress and to the Comptroller General of the United States. EPA 

will submit a report containing this rule and other required information to the U.S. Senate, the 

U.S. House of Representatives, and the Comptroller General of the United States prior to 

publication of the rule in the Federal Register. A Major rule cannot take effect until 60 days after 

it is published in the Federal Register. This action is not a “major rule” as defined by 5 U.S.C. 

804(2). This rule will be effective on [Insert date 60 days from date of publication in the 

Federal Register]. 

List of Subjects

40 CFR Part 85 

Confidential business information, Imports, Labeling, Motor vehicle pollution, Reporting and 

recordkeeping requirements, Research, Warranties.
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Lisa Jackson, on May 23, 2012. We have taken steps to ensure the accuracy of this version, but it is not the official 

version.

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40 CFR Part 86 

Administrative practice and procedure, Confidential business information, Motor vehicle 

pollution, Reporting and recordkeeping requirements. 

40 CFR Part 1039 

Administrative practice and procedure, Air pollution control, Confidential business information, 

Environmental protection, Imports, Labeling, Penalties, Reporting and recordkeeping 

requirements, Warranties.

Dated: __________________________________ 

_______________________________________ 

Lisa P. Jackson

Administrator

For the reasons set forth in the preamble, the Environmental Protection Agency amends title 40, 

chapter I of the Code of Federal Regulations as follows: 

PART 85--CONTROL OF AIR POLLUTION FROM MOBILE SOURCES

1. The authority citation for part 85 continues to read as follows: 

Authority: 42 U.S.C. 7401-7671q. 

Subpart R--[Amended]

2. Add §85.1716 to subpart R to read as follows: 

§ 85.1716 Approval of an emergency vehicle field modification (EVFM).

This section describes how you may implement design changes for an emergency vehicle that 

has already been placed into service to ensure that the vehicle will perform properly in 

emergency situations. This applies for any light-duty vehicle, light-duty truck, or heavy-duty 

vehicle meeting the definition of emergency vehicle in 40 CFR 86.004-2 or 86.1803. In this 

section, “you” refers to the certifying manufacturer and “we” refers to the EPA Administrator 

and any authorized representatives. 

(a) You must notify us in writing of your intent to install or distribute an emergency vehicle field 

modification (EVFM). In some cases you may install or distribute an EVFM only with our 

advance approval, as specified in this section.

(b) Include in your notification a full description of the EVFM and any documentation to support 

your determination that the EVFM is necessary to prevent the vehicle from losing speed, torque, 

or power due to abnormal conditions of its emission control system, or to prevent such abnormal 

conditions from occurring during operation related to emergency response. Examples of such 

abnormal conditions may include excessive exhaust backpressure from an overloaded particulate 

trap, or running out of diesel exhaust fluid for engines that rely on urea-based selective catalytic 

reduction. Your determination must be based on an engineering evaluation or testing or both. 

(c) You may need our advance approval for your EVFM, as follows: 

(1) Where the proposed EVFM is identical to an AECD we approved under this part for an 

engine family currently in production, no approval of the proposed EVFM is necessary.
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Lisa Jackson, on May 23, 2012. We have taken steps to ensure the accuracy of this version, but it is not the official 

version.

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(2) Where the proposed EVFM is for an engine family currently in production but the 

applicable demonstration is based on an AECD we approved under this part for an engine 

family no longer in production, you must describe to us how your proposed EVFM differs 

from the approved AECD. Unless we say otherwise, your proposed EVFM is deemed 

approved 30 days after you notify us. 

(3) If we have not approved an EVFM comparable to the one you are proposing, you must 

get our approval before installing or distributing it. In this case, we may request additional 

information to support your determination under paragraph (b) of this section, as follows: 

(i) If we request additional information and you do not provide it within 30 days after we 

ask, we may deem that you have retracted your request for our approval; however, we 

may extend this deadline for submitting the additional information. 

(ii) We will deny your request if we determine that the EVFM is not necessary to prevent 

the vehicle from losing speed, torque, or power due abnormal conditions of the emission 

control system, or to prevent such abnormal conditions from occurring, during operation 

related to emergency response.

(iii) Unless we say otherwise, your proposed EVFM is deemed approved 30 days after we 

acknowledge that you have provided us with all the additional information we have 

specified.

(4) If your proposed EVFM is deemed to be approved under paragraph (c)(2) or (3) of this 

section and we find later that your EVFM in fact does not meet the requirements of this 

section, we may require you to no longer install or distribute it.

PART 86--CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY 

VEHICLES AND ENGINES

3. The authority citation for part 86 continues to read as follows: 

Authority: 42 U.S.C. 7401-7671q. 

Subpart A– [Amended]

4. Section 86.004-2 is amended as follows: 

a. By adding a definition for “Ambulance” in alphabetical order.

b. By revising the definition for “Defeat device”. 

c. By adding definitions for “Diesel exhaust fluid”, “Emergency vehicle”, and “Fire 

truck” in alphabetical order.

§ 86.004–2 Definitions.

* * * * * 

Ambulance has the meaning given in §86.1803. 

Defeat device means an auxiliary emission control device (AECD) that reduces the 

effectiveness of the emission control system under conditions which may reasonably be expected 

to be encountered in normal vehicle operation and use, unless: 

(1) Such conditions are substantially included in the applicable Federal emission test procedure 

for heavy-duty vehicles and heavy-duty engines described in subpart N of this part; 

(2) The need for the AECD is justified in terms of protecting the vehicle against damage or 

accident; 

(3) The AECD does not go beyond the requirements of engine starting; or

(4) The AECD applies only for engines that will be installed in emergency vehicles, and the need 

is justified in terms of preventing the engine from losing speed, torque, or power due abnormal 

conditions of the emission control system, or in terms of preventing such abnormal conditions 
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Lisa Jackson, on May 23, 2012. We have taken steps to ensure the accuracy of this version, but it is not the official 

version.

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from occurring, during operation related to emergency response. Examples of such abnormal 

conditions may include excessive exhaust backpressure from an overloaded particulate trap, and 

running out of diesel exhaust fluid for engines that rely on urea-based selective catalytic 

reduction. 

Diesel exhaust fluid (DEF) has the meaning given in §86.1803. 

Emergency vehicle means a vehicle that is an ambulance or a fire truck. 

Fire truck has the meaning given in §86.1803. 

* * * * * 

5. Section 86.0004-28 is amended by revising the introductory text of paragraph (i) to read as 

follows: 

§ 86.004-28 Compliance with emission standards.

* * * * * 

(i) Emission results from heavy-duty engines equipped with exhaust aftertreatment may need to 

be adjusted to account for regeneration events. This provision only applies for engines equipped 

with emission controls that are regenerated on an infrequent basis. For the purpose of this 

paragraph (i), the term “regeneration” means an event during which emission levels change 

while the aftertreatment performance is being restored by design. Examples of regenerations are 

increasing exhaust gas temperature to remove sulfur from an adsorber or increasing exhaust gas 

temperature to oxidize PM in a trap. For the purpose of this paragraph (i), the term “infrequent” 

means having an expected frequency of less than once per transient test cycle. Calculation and 

use of adjustment factors are described in paragraphs (i)(1)–(5) of this section. If your engine 

family includes engines with one or more AECDs for emergency vehicle applications approved 

under paragraph (4) of the definition of defeat device, do not consider additional regenerations 

resulting from those AECDs when calculating emission factors or frequencies under this 

paragraph (i).

* * * * * 

6. Section 86.095-35 is amended by revising paragraph (a)(3)(iii)(O) to read as follows: 

§ 86.095-35 Labeling. 

(a) * * * 

(3) * * * 

(iii)* * * 

(O) For engines with one or more approved AECDs for emergency vehicle applications under 

paragraph (4) of the definition of defeat device, the statement: “THIS ENGINE IS FOR 

INSTALLATION IN EMERGENCY VEHICLES ONLY.”

* * * * * 

Subpart B– [Amended]

7. Section 86.131-00 is amended by adding paragraph (g) to read as follows: 

§ 86.131-00 Vehicle preparation.

* * * * * 

(g) You may disable any AECDs that have been approved solely for emergency vehicle 

applications under paragraph (4) of the definition of defeat device. The emission standards do 

not apply when any of these AECDs are active.
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version.

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Subpart N– [Amended]

8. Section 86.1305-2010 is amended by adding paragraph (i) to read as follows: 

§ 86.1305-2010 Introduction; structure of subpart.

* * * * * 

(i) You may disable any AECDs that have been approved solely for emergency vehicle 

applications under paragraph (4) of the definition of defeat device. The emission standards do 

not apply when any of these AECDs are active.

9. Section 86.1370-2007 is amended by adding paragraph (h) to read as follows: 

§ 86.1370-2007 Not-To-Exceed test procedures. 

* * * * * 

(h) Emergency vehicle AECDs. If your engine family includes engines with one or more 

approved AECDs for emergency vehicle applications under paragraph (4) of the definition of 

defeat device, the NTE emission limits do not apply when any of these AECDs are active.

Subpart S– [Amended]

10. Section 86.1803-01 is amended as follows: 

a. By adding a definition for “Ambulance” in alphabetical order.

b. By revising the definition for “Defeat device”. 

c. By adding definitions for “Diesel exhaust fluid”, “Emergency vehicle”, and “Fire 

truck” in alphabetical order.

§ 86.1803-01 Definitions.

* * * * * 

 Ambulance means a vehicle used for emergency medical care that provides all of the 

following: 

(1) A driver’s compartment.

(2) A patient compartment to accommodate an emergency medical services provider and one 

patient located on the primary cot so positioned that the primary patient can be given intensive 

life-support during transit. 

(3) Equipment and supplies for emergency care at the scene as well as during transport.

(4) Safety, comfort, and avoidance of aggravation of the patient’s injury or illness. 

(5) Two-way radio communication. 

(6) Audible and visual traffic warning devices. 

* * * * * 

Defeat device means an auxiliary emission control device (AECD) that reduces the 

effectiveness of the emission control system under conditions which may reasonably be expected 

to be encountered in normal vehicle operation and use, unless: 

(1) Such conditions are substantially included in the Federal emission test procedure; 

(2) The need for the AECD is justified in terms of protecting the vehicle against damage or 

accident;

(3) The AECD does not go beyond the requirements of engine starting; or 
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Lisa Jackson, on May 23, 2012. We have taken steps to ensure the accuracy of this version, but it is not the official 

version.

Page 38 of 41

(4) The AECD applies only for emergency vehicles and the need is justified in terms of 

preventing the vehicle from losing speed, torque, or power due to abnormal conditions of the 

emission control system, or in terms of preventing such abnormal conditions from occurring, 

during operation related to emergency response. Examples of such abnormal conditions may 

include excessive exhaust backpressure from an overloaded particulate trap, and running out of 

diesel exhaust fluid for engines that rely on urea-based selective catalytic reduction.

* * * * * 

Diesel exhaust fluid (DEF) means a liquid compound used in conjunction with selective 

catalytic reduction to reduce NOx emissions. Diesel exhaust fluid is generally understood to 

conform to the specifications of ISO 22241. 

* * * * * 

Emergency vehicle means a vehicle that is an ambulance or a fire truck.

* * * * * 

Fire truck means a vehicle designed to be used under emergency conditions to transport 

personnel and equipment and to support the suppression of fires and mitigation of other 

hazardous situations. 

* * * * * 

11. Section 86.1807-01 is amended by adding paragraphs (h) and (i) to read as follows: 

§ 86.1807-01 Vehicle labeling.

* * * * * 

(h) Vehicles powered by model year 2007 through 2013 diesel-fueled engines must include 

permanent readily visible labels on the dashboard (or instrument panel) and near all fuel inlets 

that state “Use Ultra Low Sulfur Diesel Fuel Only” or “Ultra Low Sulfur Diesel Fuel Only”.

(i) For vehicles with one or more approved AECDs for emergency vehicles under paragraph (4) 

of the definition of defeat device, include the following statement on the emission control 

information label: “THIS VEHICLE HAS A LIMITED EXEMPTION AS AN EMERGENCY 

VEHICLE.”

12. Subpart S is amended by removing §86.1807-07. 

§86.1807-07 – [Removed]

13. Section 86.1840-01 is amended by revising paragraph (c) to read as follows: 

§ 86.1840-01 Special test procedures.

* * * * * 

(c) Manufacturers of vehicles equipped with periodically regenerating aftertreatment devices 

must propose a procedure for testing and certifying such vehicles, including SFTP testing, for the 

review and approval of the Administrator. The manufacturer must submit its proposal before it 

begins any service accumulation or emission testing. The manufacturer must provide with its 

submittal sufficient documentation and data for the Administrator to fully evaluate the operation 

of the aftertreatment devices and the proposed certification and testing procedure. 

* * * * * 

PART 1039– CONTROL OF EMISSIONS FROM NEW AND IN-USE NONROAD 

COMPRESSION-IGNITION ENGINES
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14. The authority citation for part 1039 continues to read as follows: 

Authority: 42 U.S.C. 7401-7671q. 

Subpart B– [Amended]

15. Section 1039.115 is amended by adding paragraphs (g)(4) and (g)(5) to read as follows: 

§1039.115 What other requirements apply?

* * * * * 

(g) * * * 

 (4) The auxiliary emission control device applies only for engines that will be installed in 

emergency equipment and the need is justified in terms of preventing the equipment from 

losing speed or power due to abnormal conditions of the emission control system, or in terms 

of preventing such abnormal conditions from occurring, during operation related to 

emergency response. Examples of such abnormal conditions may include excessive exhaust 

backpressure from an overloaded particulate trap, and running out of diesel exhaust fluid for 

engines that rely on urea-based selective catalytic reduction. The emission standards do not 

apply when any AECDs approved under this paragraph (g)(4) are active. 

(5) The auxiliary emission control device operates only in emergency situations as defined in 

§1039.665 and meets all of the requirements of that section, and you meet all of the 

requirements of that section.

16. Section 1039.135 is amended by adding paragraph (c)(15) to read as follows:

§1039.135 How must I label and identify the engines I produce? 

* * * * * 

(c) * * * 

(15) For engines with one or more approved auxiliary emission control devices for emergency 

equipment applications under §1039.115(g)(4), the statement: “THIS ENGINE IS FOR 

INSTALLATION IN EMERGENCY EQUIPMENT ONLY.”

* * * * * 

Subpart F– [Amended]

17. Section 1039.501 is amended by adding paragraph (g) to read as follows: 

§ 1039.501 How do I run a valid emission test? 

* * * * * 

(g) You may disable any AECDs that have been approved solely for emergency equipment 

applications under §1039.115(g)(4). 

18. Section 1039.525 is amended by revising the introductory text to read as follows: 

§ 1039.525 How do I adjust emission levels to account for infrequently regenerating 

aftertreatment devices?

This section describes how to adjust emission results from engines using aftertreatment 

technology with infrequent regeneration events. For this section, “regeneration” means an 

intended event during which emission levels change while the system restores aftertreatment 

performance. For example, exhaust gas temperatures may increase temporarily to remove sulfur 

from adsorbers or to oxidize accumulated particulate matter in a trap. For this section, 
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Lisa Jackson, on May 23, 2012. We have taken steps to ensure the accuracy of this version, but it is not the official 

version.

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“infrequent” refers to regeneration events that are expected to occur on average less than once 

over the applicable transient duty cycle or ramped-modal cycle, or on average less than once per 

typical mode in a discrete-mode test. If your engine family includes engines with one or more 

AECDs for emergency equipment applications approved under §1039.115(g)(4), do not consider 

additional regenerations resulting from those AECDs when calculating emission factors or 

frequencies under this section. 

* * * * * 

Subpart G– [Amended]

19. A new §1039.670 is added to subpart G to read as follows: 

§ 1039.670 Approval of an emergency equipment field modification (EEFM).

This section describes how you may implement design changes for emergency equipment that 

has already been placed into service to ensure that the equipment will perform properly in 

emergency situations.

(a) You must notify us in writing of your intent to install or distribute an emergency equipment 

field modification (EEFM). In some cases you may install or distribute an EEFM only with our 

advance approval, as specified in this section. 

(b) Include in your notification a full description of the EEFM and any documentation to support 

your determination that the EEFM is necessary to prevent the equipment from losing speed, 

torque, or power due to abnormal conditions of its emission control system, or to prevent such 

abnormal conditions from occurring during operation related to emergency response. Examples 

of such abnormal conditions may include excessive exhaust backpressure from an overloaded 

particulate trap, or running out of diesel exhaust fluid (DEF) for engines that rely on urea-based 

selective catalytic reduction. Your determination must be based on an engineering evaluation or 

testing or both. 

(c) You may need our advance approval for your EEFM, as follows: 

(1) Where the proposed EEFM is identical to an AECD we approved under this part for an 

engine family currently in production, no approval of the proposed EEFM is necessary. 

(2) Where the proposed EEFM is for an engine family currently in production but the 

applicable demonstration is based on an AECD we approved under this part for an engine 

family no longer in production, you must describe to us how your proposed EEFM differs 

from the approved AECD. Unless we say otherwise, your proposed EEFM is deemed 

approved 30 days after you notify us. 

(3) If we have not approved an EEFM comparable to the one you are proposing, you must get 

our approval before installing or distributing it. In this case, we may request additional 

information to support your determination under paragraph (b) of this section, as follows: 

(i) If we request additional information and you do not provide it within 30 days after we 

ask, we may deem that you have retracted your request for our approval; however, we 

may extend this deadline for submitting the additional information.

(ii) We will deny your request if we determine that the EEFM is not necessary to prevent 

the equipment from losing speed, torque, or power due abnormal conditions of the 

emission control system, or to prevent such abnormal conditions from occurring, during 

operation related to emergency response.

(iii) Unless we say otherwise, your proposed EEFM is deemed approved 30 days after we 

acknowledge that you have provided us with all the additional information we have 

specified.
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version.

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(4) If your proposed EEFM is deemed to be approved under paragraph (c)(2) or (3) of this 

section and we find later that your EEFM in fact does not meet the requirements of this 

section, we may require you to no longer install or distribute it.

Subpart I– [Amended]

20. Section 1039.801 is amended by adding definitions for “Diesel exhaust fluid” and 

“Emergency equipment” in alphabetical order to read as follows:

§ 1039.801 What definitions apply to this part? 

* * * * * 

Diesel exhaust fluid (DEF) means a liquid compound used in conjunction with selective 

catalytic reduction to reduce NOx emissions. Diesel exhaust fluid is generally understood to 

conform to the specifications of ISO 22241. 

* * * * * 

 Emergency equipment means either of the following types of equipment: 

(1) Specialized vehicles used to perform aircraft rescue and fire-fighting functions at airports, 

with particular emphasis on saving lives and reducing injuries coincident with aircraft fires 

following impact or aircraft ground fires. 

(2) Wildland fire apparatus, which includes any apparatus equipped with a slip-on fire-fighting 

module, designed primarily to support wildland fire suppression operations. 

* * * * * 

21. Section 1039.805 is amended by adding abbreviations for “DEF”, “EEFM”, “ISO”, and 

“SCR” in alphabetical order to read as follows:

§ 1039.805 What symbols, acronyms, and abbreviations does this part use? 

* * * * * 

DEF Diesel exhaust fluid.

EEFM Emergency equipment field modification. 

* * * * * 

ISO International Organization for Standardization (see www.iso.org). 

* * * * * 

SCR Selective catalytic reduction.

* * * * *