Heavy Trucks, Buses, and Engines
You will need Adobe Acrobat Reader to view the Adobe PDF files on this page. See EPA's PDF page for more information about getting and using the free Acrobat Reader.
This page presents emission-related information about heavy-duty highway engines, such as those used in trucks and buses. Much of this content is focused on diesel engines, but requirements also apply for gasoline-fueled and other spark-ignition engines. The requirements apply to engines installed in all vehicles with Gross Vehicle Weight Rating above 14,000 pounds, and to some engines installed in vehicles with Gross Vehicle Weight Rating between 8,500 and 14,000 pounds. This page describes the emission standards and related requirements for criteria pollutants -- NOx, HC, CO, and PM. See Greenhouse Gas Standards for requirements that apply for CO2, N2O, and CH4.
- General Information
- Regulations and Related Documents
- Certification Guidance
- Additional Provisions
- Related Links
General Information
- National Clean Diesel Campaign Publications
- Health Assessment Document for Diesel Engine Exhaust
- 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 CI exhaust emission standards, SI exhaust emission standards, and evaporative emission standards
- Nonconformance Penalties for On-Highway Heavy-Duty Diesel Engines (signed August 30, 2012)
- Emergency Vehicle and SCR Maintenance Rule (published June 8, 2012)
EPA’s direct final rule for emergency vehicles went into effect August 7, 2012, allowing manufacturers of engines for fire trucks and ambulances to request modifications to emission control systems so they do not interfere with emergency missions. In a parallel action, EPA also proposed revisions to establish minimum maintenance intervals for urea refills with SCR systems. EPA also proposed short-term relief for general purpose nonroad equipment during emergencies. A public hearing was held June 27, and the comment period ended July 27. Public comments and the hearing transcript are available in the rulemaking docket.- 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 Nonroad Diesel Engines for more information about similar rulemaking changes for nonroad engines
- 2010 Technical Amendments -- In-Use Testing Revisions (published November 8, 2010)
- Direct Final Rule (PDF) (20 pp, 366k)
- See In-use Testing for more information.
- Greenhouse Gas Reporting Rule (published October 30, 2009)
- Final Rule (PDF) (260 pp, 1.40MB)
- See Greenhouse Gas Reporting for more information.
- 2008 Technical Amendments -- Nonroad SI Rule (published October 8, 2008)
- Final Rule (PDF) (343 pp, 3.7MB)
- See Nonroad SI Rule for more information
- 2008 Technical Amendments -- Locomotive-Marine Rule (published June 30, 2008)
- Final Rule (PDF) (255 pp, 2.10MB)
- See Locomotive-Marine Rule for more information
- 2006 Technical Amendments (published August 30, 2006)
- Fact Sheet: Highway Heavy-Duty Diesel Engine Regulatory Amendments (PDF) (9 pp, 215K, EPA-420-F-06-059, August 2006)
- Direct Final Rule (PDF) (9 pp, 219K)
- 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, EPA-420-F-05-036, July 2005)
- Final Rule (PDF) (193 pp, 7.48MB)
- Technical Support Document and Summary and Analysis of Comments (PDF) (115 pp, 1,663K, EPA420-R-05-008, June 2005)
- See Proposed Technical Amendments for the proposed rule and supporting documents (published September 10, 2004)
- Final Rule: 2007 and 2010 Model Year Standards (published January 18, 2001)
- Fact Sheet: Heavy-Duty Engine and Vehicle Standards and Highway Diesel Fuel Sulfur Control Requirement (PDF) (4 pp, 120K, EPA-420-F-00-057, December 2000)
- Fact Sheet: Introduction of Cleaner-Burning Diesel Fuel Enables Advanced Pollution Control for Cars, Trucks, and Buses (PDF) (3 pp, 172K, EPA420-F-06-064, October 2006)
- Final Rule (PDF) (192 pp, 1.71MB)
- Regulatory Impact Analysis
- Technical Support Document: Air Quality Modeling Analyses (PDF) (107 pp, 320K, EPA-420-R-00-028, December 2000)
- Response to Comments (PDF) (152 pp, 120K, EPA-420-F-00-057, December 2000)
See Proposed Emission Standards for proposed rule, fact sheets, and regulatory support documents.
Certification Guidance
- Approval of New Scheduled Maintenance for Selective Catalyst Reduction Technologies (PDF) (4 pp, 145K, published November 9, 2009)
- Approval of New Scheduled Maintenance for Diesel Particulate Filters (PDF) (3 pp, 186K, published March 7, 2006)
- 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)
Additional Provisions
- Nonconformance penalties
- Greenhouse gas standards
- On-board Diagnostic regulations
- Manufacturer-run In-use Testing
Related Links to EPA information
- Certification Data
- Hardship Exemptions
- Certification Fees
- Test Procedures
- Diesel Engine Settlement Information (Office of Civil Enforcement)
- In-use Fuel
- Imports of Vehicles, Engines and Equipment
- Nonroad Diesel Equipment
- National Clean Diesel Campaign
- Clean Schoolbus USA
- SmartWay