DEF Act

This bill amends the Clean Air Act for cars, trucks, heavy-duty engines, and nonroad diesel engines and equipment. For 10 years, vehicle and engine makers that follow certain EPA guidance documents on diesel exhaust fluid (DEF) warning systems, engine power limits, quality monitoring, and repair overrides would not be treated as breaking the law. During those 10 years, the EPA could not adopt or authorize, including through state waivers, emission standards stricter than the 2007, 2010, and Tier 4 standards in effect on January 1, 2025, though it could still enforce rules against tampering and defeat devices. After the 10 years, any new standards would have to be announced at least 5 model years before taking effect and last at least 3 model years, and the EPA would have to consider costs and effects on owners, operators, and equipment.

Full text and official record on Congress.gov

Sponsors

• Julie Fedorchak Republican sponsor
• 7 cosponsors