Stop CARB Act of 2025

This bill amends the Clean Air Act to eliminate the ability of the Environmental Protection Agency (EPA) to grant waivers allowing California to set its own motor vehicle emission standards, and also repeals the authorization for other states to adopt California's standards. It prohibits states from setting emission standards for certain nonroad engines and vehicles, such as those used in construction and farm equipment, and for locomotives.

Sec. 2, Repeal of waivers of state standards: This section strikes the existing waiver provision (subsection (b)) from the Clean Air Act, meaning no new waivers can be issued. Any waiver issued before the bill's enactment date is void, and any pending waiver application is considered denied. It also adds a new prohibition preventing states from adopting emission standards for nonroad engines or vehicles, specifically including new engines used in construction, farm equipment, and locomotives. Several other sections of the Clean Air Act are amended to remove references to these waivers.

Sec. 3, Repeal of authorization to use California new motor vehicle emission standards: This section repeals Section 177 of the Clean Air Act, which allowed other states to adopt California's stricter motor vehicle emission standards. A related conforming amendment is made to another section of the Act.