DEF Act

Key Points

• The bill stops EPA from making diesel emission rules stricter than current 2007/2010 on-road standards and Tier 4 nonroad standards for 10 years after it becomes law.
• It shields manufacturers and equipment owners from penalties when they follow existing EPA guidance on inducement strategies and diesel exhaust fluid quality monitoring, which is meant to prevent engines from being wrongly forced into shutdown or power-reduction modes.
• After the 10 year freeze, any new emission standard must apply for at least 3 model years and cannot take effect sooner than 5 years after it is issued, giving industry advance notice.
• Before issuing future rules, EPA must consider effects on repair costs, resale value, dealer inventories, and the need for nationally consistent requirements, aiming to limit financial strain on truck owners, farmers, and small operators.
• The bill also restricts EPA authority under Clean Air Act section 209(b), the same provision California uses to get waivers for stricter state vehicle emission standards, freezing that pathway for a decade.