Engine Testing Regulations
On this page:
Overview
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.
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.
Test procedures are available at 40 CFR part 1065.
IMPORTANT NOTE: When EPA makes changes to 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.
For more information about the format of emission regulations, including the standard-setting part for each type of engine, see:
- Resource Information: Plain Language Format of Emission Regulations for Mobile Sources (pdf) (215 KB, EPA-420-F-22-011, March 2022)
Applicable Engine Test Procedures for Each Engine Category
The following table has engine test procedures from the standard-setting part for each engine category. For ease of use, Electronic Code of Federal Regulations (e-CFR) links are provided.
| Vehicle Category Description | Corresponding Regulation Page | e-CFR Link(s) for the Standard-Setting Part |
|---|---|---|
| Heavy-Duty Highway Engines | Regulations for emissions from commercial trucks and buses (heavy-duty) |
|
| Locomotives | Regulations for emissions from locomotives | |
| Marine Diesel Engines (Diesel Boats and Ships) |
Regulations for emissions from marine vessels with compression-ignition (diesel) engines | |
| Other Nonroad and Stationary Diesel Engines | Regulations for emissions from heavy equipment with compression-ignition (diesel) engines | |
| Recreational Vehicles (Snowmobiles and some Dirt Bikes and ATVs) |
Regulations for emissions from recreational vehicles | |
| Marine Spark-Ignition Engines (Gasoline Boats and Personal Watercraft) |
Regulations for emissions from marine vessels with spark-ignition engines | |
| Other Nonroad and Stationary Spark-Ignition Engines at or below 19kW (Lawn and Garden) |
Regulations for emissions from small equipment and tools | |
| Other Nonroad and Stationary Spark-Ignition Engines above 19 kW (Forklifts, Generators and Compressors) |
Regulations for emissions from heavy equipment with spark-ignition engines | |
| Stationary Compression-Ignition Engines | New Source Performance Standards for Stationary Compression Ignition Internal Combustion Engines |
|
| Stationary Spark-Ignition Engines | New Source Performance Standards for Stationary Spark Ignition Internal Combustion Engines |
|
List of Related Regulations
40 CFR part 1065 provides regulations for the required testing procedures for engines. The following list of regulations shows all the changes made to part 1065.
Help
For help on using the table:
- Regulations;
- Regulatory impact analyses;
- Comment summaries;
- Rule histories (including proposed rules); and/or
- Fact sheets.
NOTE: Rule-related materials vary by rule.
| Regulation Title | Summary of Rule and Applicability to Testing | Regulation Publish Date (Year/Month) |
|---|---|---|
| Greenhouse Gas Emissions Standards for Heavy-Duty Vehicles—Phase 3 | This rule included minor amendments to part 1065, mostly to account for the revised test procedures for the greenhouse gas emission standards for heavy-duty engines. | 2024/04 |
| Control of Air Pollution From New Motor Vehicles: Heavy-Duty Engine and Vehicle Standards | This rule included minor amendments to part 1065, mostly to account for the new and revised test procedures for the criteria pollutant emission standards for heavy-duty engines. | 2023/01 |
| Improvements for Heavy-Duty Engine and Vehicle Test Procedures, and Other Technical Amendments | This rule included minor amendments to part 1065 related to how to measure emissions from heavy-duty engines to reduce variability associated with the test procedures. | 2021/06 |
| Fuels Regulatory Streamlining | This rule included minor amendments to reference the new 40 CFR 1090 for in-use fuel standards and updates to the fuel sulfur measurement methods for distillate diesel fuel. | 2020/12 |
| Greenhouse Gas Emissions and Fuel Efficiency Standards for Medium- and Heavy-Duty Engines and Vehicles - Phase 2 | This rule included minor amendments to part 1065, mostly to account for the new and revised test procedures for the greenhouse gas emission standards for heavy-duty engines. | 2016/10 |
| Amendments Related to Tier 3 Motor Vehicle Emission and Fuel Standards, Nonroad Engine and Equipment Programs, and MARPOL Annex VI Implementation | This rule included minor amendments to part 1065, mostly to correct and clarify provisions associated with the Tier 3 standards for motor vehicles. | 2015/02 |
| Final Rule for Control of Air Pollution from Motor Vehicles: Tier 3 Motor Vehicle Emission and Fuel Standards | 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. | 2014/04 |
| Final Rule: Incorporation of Revised ASTM Standards That Provide Flexibility in the Use of Alternatives to Mercury-Containing Industrial Thermometers (pdf) (196 KB, published January 18, 2012) | This rule included updated references to ASTM procedures related to mercury content in thermometers. | 2012/01 |
| Final Rule for Greenhouse Gas Emissions Standards and Fuel Efficiency Standards for Medium- and Heavy-Duty Engines and Vehicles | 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. | 2011/09 |
| Final Rule for Control of Emissions From New Marine Compression-Ignition Engines at or Above 30 Liters per Cylinder | This rule applied part 1065 to Category 3 marine compression-ignition engines. The rule also included several amendments to part 1065. | 2010/04 |
| Direct Final Rule for Revisions to In-Use Testing for Heavy-Duty Diesel Engines and Vehicles; Emissions Measurement and Instrumentation; Not-to-Exceed Emission Standards; and Technical Amendments for Off-Highway Engines | This rule included minor amendments to part 1065. | 2010/11 |
| Final Rule for Mandatory Reporting of Greenhouse Gases | This rule included minor amendments to part 1065. | 2009/10 |
| Final Rule for Control of Air Pollution From New Motor Vehicles and New Motor Vehicle Engines; Regulations Requiring Onboard Diagnostic Systems on 2010 and Later Heavy-Duty Engines Used in Highway Applications Over 14,000 Pounds | This rule included minor amendments to part 1065. | 2009/02 |
| Final Rule for Control of Emissions From Nonroad Spark-Ignition Engines and Equipment | 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. | 2008/10 |
| Final Rule Republication for Control of Emissions of Air Pollution From Locomotive Engines and Marine Compression-Ignition Engines Less Than 30 Liters per Cylinder | This rule applied part 1065 to locomotive and marine compression-ignition engines and included extensive amendments. | 2008/06 |
| Final Rule: Standards of Performance for Stationary Spark Ignition Internal Combustion Engines and National Emission Standards for Hazardous Air Pollutants for Reciprocating Internal Combustion Engines (pdf) (338 KB, published January 18, 2008) | This rule applied part 1065 to stationary spark-ignition engines.& | 2008/01 |
| Standards of Performance for Stationary Compression Ignition Internal Combustion Engines (pdf) (286 KB, published July 11, 2006) | This rule applied part 1065 to stationary compression-ignition engines. | 2006/07 |
| Final Rule for Procedures for Testing Highway and Nonroad Engines and Omnibus Technical Amendments | This rule involved a comprehensive set of amendments to part 1065. | 2005/07 |
| Final Rule for Control of Emissions of Air Pollution From Nonroad Diesel Engines and Fuel | This rule applied part 1065 to nonroad compression-ignition engines and included minor amendments. | 2004/06 |
| Final Rule for Control of Emissions From Nonroad Large Spark-Ignition Engines, and Recreational Engines (Marine and Land-Based) | This was the initial publication of part 1065. | 2002/11 |