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Nonroad Diesel Engines
Nonroad diesel engines are used in machines that perform a wide range of important jobs. These include excavators and other construction equipment, farm tractors and other agricultural equipment, heavy forklifts, airport ground service equipment, and utility equipment such as generators, pumps, and compressors.
We have adopted multiple tiers of emission standards. Most recently, we adopted a comprehensive national program to reduce emissions from nonroad diesel engines by integrating engine and fuel controls as a system to gain the greatest emission reductions. To meet these Tier 4 emission standards, engine manufacturers will produce new engines with advanced emission control technologies similar to those already expected for highway trucks and buses. Exhaust emissions from these engines will decrease by more than 90 percent. Because the emission control devices can be damaged by sulfur, we have also adopted requirements for in-use diesel fuel to decrease sulfur levels by more than 99 percent. The resulting Ultra Low Sulfur Diesel Fuel has a maximum sulfur concentration of 15 parts per million. For a more extensive consideration of health issues related to diesel engines, see EPA’s Health Assessment Document for Diesel Engine Exhaust.
The following page links help you to:
- General Information
- Regulations and Related Documents
- Certification Guidance
- Duty Cycles for Engine Testing
- Related Links
General Information
- National Clean Diesel Campaign Publications
- Emission Standards and Owner Responsibilities (PDF) (4 pp, 158K, EPA-420-F-12-053, August 2012)
- How to Maintain or Rebuild Engines Certified to EPA Standards (PDF) (4 pp, 142K, EPA-420-F-12-052, August 2012)
Regulations and Related Documents
- Summary of emission standards
- Emergency Vehicle and SCR Maintenance Rule
EPA’s direct final rule for emergency vehicles went into effect August 7, 2012, allowing manufacturers of engines for dedicated nonroad emergency equipment to request modifications to emission control systems so they do not interfere with emergency vehicles’ missions. In a parallel action, EPA proposed to establish minimum maintenance intervals for urea refills with SCR systems for nonroad engines. EPA also proposed short-term relief for general purpose nonroad equipment so that emission controls do not hinder the engine’s performance in emergency situations.- Fact Sheet: EPA Grants Relief for Fire Trucks and Ambulances; Proposes SCR Maintenance and Short-Term Relief for Nonroad Equipment (PDF) (4 pp, 560K, EPA420-F-12-025, May 2012)
- Direct Final Rule (PDF) (19 pp, 603K, published June 8, 2012)
- Notice of Proposed Rulemaking (PDF) (30 pp, 602K, published June 8, 2012)
- See Highway Engines for more information about similar rulemaking changes for heavy-duty highway engines
- November 2010 Amendments (published November 8, 2010)
- Final Rule (PDF) (20 pp, 366k)
- See Heavy-duty Highway Engines for more information.
- April 2010 Technical Amendments (published April 30, 2010)
- Final Rule (PDF) (171 pp, 3.66MB)
- See Marine Diesel final rule for more information. See especially Chapter 11 of the Summary and Analysis of Comments.
- Greenhouse Gas Reporting Rule (published October 30, 2009)
- Final Rule (PDF) (260 pp, 1.40MB)
- See Greenhouse Gas Reporting for more information.
- October 2008 Technical Amendments (published October 8, 2008)
- Final Rule (PDF) (347 pp, 3.69MB)
- See Nonroad SI final rule for more information
- June 2008 Amendments (published June 30, 2008)
- Final Rule (PDF) (347 pp, 3.69MB)
- See Locomotive-Marine Rule for more information
- Final 2007 Technical Amendments (published September 18, 2007)
- Fact Sheet (PDF) (3 pp, 103K, EPA420-F-07-055, September 2007)
- Direct Final Rule (PDF) (17 pp, 250K, published September 18, 2007)
- Partial Removal of Direct Final Rule and Revised Amendments in §89.102(i) (PDF) (4 pp, 190K, published December 26, 2007)
- Emission Standards for Stationary Compression-ignition Engines (published July 11, 2006)
- Final Rule (PDF) (32 pp, 318K)
- See Stationary CI Engines for more information
- Procedures for Testing Highway and Nonroad Engines and Omnibus Technical Amendments (published July 13, 2005)
- Fact Sheet: Regulatory Announcement: Changed Test Procedures for Nonroad Engines and Heavy-Duty Highway Engines (PDF) (4 pp, 134K, EPA420-F-05-036, July 2005)
- Final Rule (PDF) (193 pp, 7.48MB)
- Technical Support Document and Summary & Analysis of Comments (PDF) (115 pp, 1.66MB, EPA420-R-05-008, June 2005)
- See Proposed Technical Amendments for the proposed rule and supporting documents (published September 10, 2004)
- Tier 4 Emission Standards (published June 29, 2004)
- Press Release: Tier 4 Standards a Major Step in a Decade of Progress (May 11, 2004)
- Fact Sheet: Tier 4 Standards (PDF) (5 pp, 122K, EPA420-F-04-032, May 2004)
- Final Rule (PDF) (316 pp, 1.87MB)
- Regulatory Impact Analysis (PDF) (1,568 pp, 8.5MB, EPA420-R-04-007, May 2004)
- Summary and Analysis of Comments (PDF) (567 pp, 1.9MB, EPA420-R-04-008, May 2004)
- See Tier 4 Proposed Rule for the proposed rule and supporting documents (published May 23, 2003)
- 2002 Technical Amendments to 40 CFR part 89 (published November 8, 2002)
- Final Rule (PDF) (206 pp, 1.15MB)
- See the final rule page for other related documents regarding the final rule
- Tier 2 and Tier 3 Emission Standards (published October 23, 1998)
- Fact Sheet (PDF) (3 pp, 13K, EPA420-F-98-034, August 1998)
- Questions and Answers (PDF) (3 pp, 14K)
- Final Rule (PDF) (56 pp, 683K)
- Final Regulatory Impact Analysis (PDF) (137 pp, 651K, EPA420-R-98-016, August 1998)
- Summary and Analysis of Comments (PDF) (117 pp, 343K, August 1998)
- See Proposed Emission Standards for the proposed rule, fact sheets, and regulatory support documents.
- 1996 Technical Amendments to Add Replacement-Engine Exemption (published November 12, 1996)
- Direct Final Rule (PDF) (6 pp, 132K)
- Tier 1 Emission Standards, and Determination of Significance for Nonroad Sources (published June 17, 1994)
- Final Rule
- Regulatory Impact Analysis (PDF) (160 pp, 566K, May 1994)
See the Electronic Code of Federal Regulations (e-CFR) for the full text of current regulations that apply to nonroad diesel engines:
40 CFR part 1039 Tier4 emission standards and certification requirements 40 CFR part 1065 Exhaust emission test procedures (for lab and in-field testing) 40 CFR part 1068 General Compliance Provisions 40 CFR part 89 Tier 3 and earlier emission standards and compliance program
Certification Guidance:
- Approval of New Scheduled Maintenance for Selective Catalytic Reduction Technologies (PDF) (3 pp, 152K, published January 5, 2012)
- Guidance on Reporting and Evaluating Auxiliary Emission Control Devices and the Defeat Device Prohibition of the Clean Air Act (PDF) (36 pp, 13.6MB, VPCD-98-13, October 15, 1998)
Duty Cycles for Engine Testing:
EPA adopted a Nonroad Transient Composite Cycle along with the Tier 4 emission standards. For application-specific cycles that were used to derive the certification duty cycle and are still used for other testing, see Nonregulatory Nonroad Duty Cycles.