The Clean Truck Check Program is California's initiative to reduce emissions from heavy-duty trucks and buses. It requires periodic emissions testing and compliance verification for vehicles operating in the state to ensure they meet air quality standards.

The program applies to heavy-duty trucks and buses with a gross vehicle weight rating (GVWR) over 14,000 pounds that operate in California. This includes both California-based and out-of-state vehicles.

The clean Truck Check includes OBD (On-Board Diagnostics) testing and opacity tests for diesel-powered vehicles to measure emissions levels. The OBD test checks if the vehicle's emission control systems are functioning correctly, while the opacity test measures exhaust smoke.

Most heavy-duty vehicles are required to undergo testing twice a year. Then, after 3 years, four times a year.

If your truck fails the test, you must repair it and pass a follow-up test to avoid penalties or restrictions on operating the vehicle in California.

Yes, out-of-state vehicles operating in California are subject to the same Clean Truck Check regulations and must be tested and compliant to operate in the state.

Testing can be conducted at licensed facilities, or mobile compliance testers like Valencia Smog.

Vehicle owners must register through the CARB Truck Regulation Upload, Compliance, and Reporting System (TRUCRS) to submit compliance data and ensure ongoing eligibility to operate in California.

By ensuring trucks meet stringent emissions standard, the program reduces pollutants like nitrogen oxides, (NOx) and particulate matter (PM), contributing to cleaner air and helping California meet its climate goals.