The Clean Truck Check program, initiated by the California Air Resources Board (CARB), requires periodic emissions testing for heavy-duty vehicles over 14,000 pounds to ensure their emissions control systems are functioning properly. The goal of this program is to lessen the air pollution caused by these cars on Californian highways.
The program applies to most heavy-duty diesel and alternative fuel vehicles over 14,000 pounds, regardless of whether they are registered in California or out of state. Exemptions exist for certain categories, such as zero-emission vehicles and some new vehicles with low NOx emissions.
Vehicle owners must register their vehicles in the Clean Truck Check database by July 1, 2024, which is the first significant deadline. Emissions compliance testing starts on October 1, 2024 (Note: As of August 2024, the California Department of Motor Vehicles has started placing registration holds on vehicles that have not passed a Clean Truck Check inspection). One test is required for vehicles in the first year. By the third year, vehicles must pass four tests a year to guarantee ongoing emissions compliance monitoring.
Compliance is enforced through annual reporting and testing requirements. Vehicles must be tested by a CARB-credentialed tester, and any vehicle that fails to meet the standards must be repaired to pass subsequent tests. Failure to comply may result in fines and limits on vehicle operating in California.
Fines, suspensions of the vehicle’s registration, and possible prohibitions on using the vehicle in California are all possible outcomes of noncompliance. Vehicles that do not pass emissions tests are also subject to repair and retesting requirements.
Starting January 1st, 2025-26, all semi-trucks will require testing twice a year. Buses, motorhomes for recreational use or emergency occupancy, and agricultural vehicles will need testing once per year. Almost all other vehicles will remain subject to semi-annual testing.
Beginning October 2027, vehicles equipped with on-board diagnostics (OBD) will be required to undergo testing four times per year to comply with updated regulations.
To help vehicle owners comprehend and adhere to the program’s standards, CARB offers resources like technical support, certified tester lists, and instructions. For more details, visit the CARB Clean Truck Check page at https://ww2.arb.ca.gov/overview-fact-sheet-clean-truck-check.
A “Clean Truck Check” is required for nearly all diesel and alternative fuel heavy-duty vehicles with a gross vehicle weight rating (GVWR) exceeding 14,000 pounds that operate on California public roads, including trucks, buses, motorhomes, and agricultural vehicles, even if they are not registered in California; essentially, any large non-gasoline vehicle operating in the state needs to comply with the Clean Truck Check program.
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