Jump to main content or area navigation.

Contact Us

Testing and Measuring Emissions

Engine Testing Regulations

EPA has adopted emission standards for almost every kind of engine, including everything from lawn mowers to cruise ships. To show compliance with these emission standards, engine manufacturers must follow test procedures specified in the Code of Federal Regulations. This page provides links to the appropriate regulatory citations and includes published information related to the test procedures. These links include a general set of instructions and requirements for manufacturers to measure emissions for certifying their engines to EPA emission standards. Manufacturers should also read the regulations for category-specific provisions that apply; see our fact sheet (PDF) (6 pp, 243K, EPA-420-F-12-054, August 2012) to find the standard-setting part for each type of engine.

The test procedures referenced on this page are related to engine-based exhaust emission standards.  All types of engines are subject to the procedures in 40 CFR part 1065, excluding aircraft engines and those that require vehicle testing, though these procedures continue to be optional during a transition period for some engines.

See Vehicle Testing Regulations for information on testing for exhaust and evaporative emissions using chassis-based test procedures.

The following table shows which engine test procedures apply for each category:

Engine Category Code of Federal Register Citation
Heavy-Duty Highway Engines 40 CFR part 1065: standard-setting part is 40 CFR part 86, subparts A and N for criteria pollutants, and 40 CFR part 1036 for greenhouse gases.
Locomotives 40 CFR part 92, subpart B (through 2014, with approval)
40 CFR part 1065 (optional through 2014, mandatory starting January 1, 2015
Marine Diesel Engines (Diesel Boats and Ships) 40 CFR part 94, subpart B (through 2014, with approval)
40 CFR part 1065 (optional through 2014, mandatory starting January 1, 2015)
Other Nonroad and Stationary Diesel Engines

40 CFR part 89, subparts D and E (Tier 3 and earlier)
40 CFR part 1065 (optional for Tier 3 and earlier; mandatory for Tier 4)

Recreational Vehicles (Snowmobiles and some Dirt Bikes and ATVs) 40 CFR part 1065
Marine Spark-Ignition Engines (Gasoline Boats and Personal Watercraft) 40 CFR part 1065
Other Nonroad and Stationary Spark-Ignition Engines at or below 19kW (Lawn and Garden) 40 CFR part 1065
Other Nonroad and Stationary Spark-Ignition Engines above 19 kW (Forklifts, Generators and Compressors) 40 CFR part 1065
See 40 CFR part 60, subpart JJJJ, for unique procedures that apply for certain stationary spark-ignition 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.

The original regulations for part 1065 were adopted in 2002.  EPA has amended these regulations in several subsequent rulemakings, both to expand the scope of engines covered by part 1065 and to improve the procedures.  The current part 1065 procedures are available in the electronic Code of Federal Regulations.  Note that when we make changes to the part 1065 test procedures, manufacturers that are already subject to testing under part 1065 may take up to 12 months to comply with the new specifications.  The following list of final rules includes all the changes we have made to part 1065.  For the most recent rules, the description includes the specific dates on which compliance with the regulatory changes become mandatory.

For further information or assistance regarding this web page, please contact Alan Stout, phone: (734) 214-4805 or email: stout.alan@epa.gov.

This page is maintained by EPA's Office of Transportation and Air Quality (OTAQ).
For more: About Us | Get E-mail Updates | Browse the A to Z Subject Index.

Jump to main content.