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The U.S. Environmental Protection Agency (EPA) is issuing two actions regarding technical adjustments to improve testing procedures for vehicle and engine emissions programs. These amendments will increase compliance flexibility, improve harmonization with other requirements, increase clarity, correct errors, and remove outdated and unnecessary regulatory text.

“The Trump Administration continues its efforts to reduce the regulatory burdens on domestic industries that are vital to the American way of life,” said EPA Administrator Andrew Wheeler. “These changes help streamline EPA’s existing regulations while reducing the likelihood that manufacturers would need to duplicate certifications to comply with EPA, Canadian, and California standards.”

The first action is a final rulemaking that will reduce testing burden and improve accuracy of required emissions testing procedures for heavy duty vehicles and engines. The action also amends test procedures for exhaust emissions standards for light-duty vehicles, heavy-duty vehicles, highway motorcycles, locomotives, marine engines, other nonroad engines and vehicles, and stationary engines. Many of these updates will take effect for MY 2021.

EPA is also issuing a supplemental notice of proposed rulemaking (SNPRM) that would issue corrections, clarifications, flexibilities, and adjustment factors to improve the Greenhouse gas Emissions Model (GEM) compliance tool for heavy-duty vehicles. The proposed amendments concerning GEM included in this notice would be required for model year 2022 and later vehicles and optional for model year 2021. EPA is taking public comment on the supplemental notice of proposed rulemaking for 30 days after the notice is published in the Federal Register.


Final heavy-duty technical amendments:

Supplemental notice of proposed rulemaking:



If you are a manufacturer with issues related to emissions compliance, contact us today to speak with our team of certification experts.