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; to fine the standard-setting part for each type of engine, see: Resource Information:  Plain Language Format of Emission Regulations for Nonroad Engines (PDF)(6 pp, 243K, EPA-420-F-12-054, August 2012). 

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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:

Regulations

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.

• February 19, 2015 Direct Final Rule (PDF)(48 pp, 1.04MB)

  This rule included minor amendments to part 1065, mostly to correct and clarify provisions associated with the Tier 3 standards for motor vehicles. See “2015 Amendments” for additional rulemaking documents. These amendments became legally effective on May 5, 2015, though they do not become mandatory until May 5, 2016 under §1065.10(c)(6).

• April 28, 2014 Final Rule (PDF) (474 pp, 6.59MB)

  This rule included new standards for motor vehicles subject to vehicle-based emission standards and test procedures, and included a wide range of amendments to part 1065. See Tier 3 Final Rule for additional rulemaking documents.

• January 18, 2012 Final Rule (PDF) (120 pp, 1.25MB)

  This rule included updated references to ASTM procedures related to mercury content in thermometers.

• September 15, 2011 Final Rule (PDF) (409 pp, 4.90MB)

  This rule expanded part 1065 to apply for measurement of greenhouse gas emissions, including more detailed provisions for testing hybrid engine configurations. The rule also included several amendments to part 1065. See Heavy-Duty Greenhouse Gas Final Rule for additional rulemaking documents.

• April 30, 2010 Final Rule (PDF)(171 pp, 3.66MB)

  This rule applied part 1065 to Category 3 marine compression-ignition engines. The rule also included several amendments to part 1065. See Category 3 Marine Diesel Final Rule for additional rulemaking documents.

• November 8, 2010 Final Rule (PDF) (20 pp, 366K)

  This rule included minor amendments to part 1065. See Heavy-duty In-use Testing for additional rulemaking documents.

• October 30, 2009 Final Rule (PDF) (260 pp, 1.40MB)

  This rule included minor amendments to part 1065. See Greenhouse Gas Reporting Rule for additional rulemaking documents.

• February 24, 2009 Final Rule (PDF) (119 pp, 824K)

  This rule included minor amendments to part 1065. See Heavy-duty Highway OBD Rule for additional rulemaking documents.

• October 8, 2008 Final Rule (PDF) (347 pp, 3.65MB)

  This rule applied part 1065 to marine spark-ignition engines and nonroad spark-ignition engines at or below 19 kW. The rule also included extensive amendments to part 1065. See Nonroad and Stationary Spark-Ignition Engines at or below 19kW (Lawn and Garden) for additional rulemaking documents.

• June 30, 2008 Final Rule (PDF) (255 pp, 2.10MB)

  This rule applied part 1065 to locomotive and marine compression-ignition engines and included extensive amendments. See Locomotive-Marine Diesel Rule for additional rulemaking documents.

• January 18, 2008 Final Rule (PDF) (47 pp, 370K)

  This rule applied part 1065 to stationary spark-ignition engines. 

• July 11, 2006 Final Rule (PDF) (32 pp, 326K)

  This rule applied part 1065 to stationary compression-ignition engines.  

• July 13, 2005 Final Rule (PDF) (193 pp, 7.48K)

  This rule involved a comprehensive set of amendments to part 1065.  See Nonroad and Stationary Spark-Ignition Engines above 19 kW (Forklifts, Generators and Compressors) for additional supporting documents.

• June 29, 2004 Final Rule (PDF) (316 pp, 1.87MB)

  This rule applied part 1065 to nonroad compression-ignition engines and included minor amendments.  See Nonroad Diesel Tier 4 Rule for additional rulemaking documents.

• November 8, 2002 Final Rule (PDF) (206 pp, 1.15MB)

  This was the initial publication of part 1065.  See Nonroad and Stationary Spark-Ignition Engines above 19 kW (Forklifts, Generators and Compressors) for additional rulemaking documents.