Jump to main content or area navigation.

Contact Us

Nonroad Engines, Equipment, and Vehicles

Nonroad Diesel Engines

steam shovel is moving soil to a on-highway truck.

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:

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.

General Information

Regulations and Related Documents

top of page

Certification Guidance:

top of page

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.

top of page

top of page

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.