DEF Act Diesel Engine Flexibility Act
To amend the Clean Air Act to preserve regulatory stability for motor vehicles, motor vehicle engines, nonroad vehicles, and nonroad engines, and for other purposes.
The DEF Act, or Diesel Engine Flexibility Act, proposes to change the Clean Air Act to ensure consistent regulations for diesel engines used in cars, trucks, and other nonroad vehicles. This means that the rules governing how clean these engines need to be will stay the same, helping manufacturers and consumers plan for the future without unexpected changes. The bill affects vehicle and engine manufacturers, businesses that rely on these vehicles, and anyone concerned with air quality and emissions standards.
The bill was introduced on July 9, 2026, and was referred to the House Subcommittee on Environment and the House Committee on Energy and Commerce for further review. As of July 14, 2026, the subcommittee held a meeting to discuss and make initial changes to the bill, which was then forwarded to the full committee by voice vote. This marks the current status of the bill in the legislative process.
Key actions so far include the introduction of the bill, its referral to relevant committees, and the subcommittee's initial review. Future steps will involve further committee discussions, potential amendments, and votes before it can move to the full House for consideration.
