An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

Regulations for Emissions from Vehicles and Engines

Final Rule for Technical Amendments to the Highway and Nonroad Diesel Regulations

On this page:

Rule Summary

EPA is taking direct final action to correct, amend, and revise certain provisions of the Highway Diesel Rule, and the Nonroad Diesel Rule. This action corrects additional errors and omissions from the previous rules, and it makes minor changes to the regulations to assist entities with regulatory compliance. This action also makes technical amendments that resulted from discussions with various diesel stakeholders. These technical amendments will: provide a temporary increase in the sulfur testing tolerance, revise the designate and track provisions to account for non-petroleum diesel fuels (i.e., biodiesel) and fuel that meets the California Air Resources Board’s diesel fuel standards, and amend the alternative defense provisions to account for conductivity additives and red dye. This action is intended to help facilitate compliance with the diesel fuel regulations and ensure a smooth transition to ultra low sulfur diesel fuel.

Regulations for Emissions from Vehicles and Engines Home