California Air Resources Board

The Heavy-Duty Inspection and Maintenance program, also known as Clean Truck Check (CTC), requires all vehicle owners with heavy-duty trucks over 14,000 pounds gross vehicle weight rating (GVWR) that operate in California to ensure their emissions control systems remain well-maintained and function properly, throughout a vehicle’s useful life to reduce harmful emissions. The program requires fleets to report operation in California and conduct regular testing, similar to the light duty vehicle smog program. Vehicles are also subject to roadside inspections and emissions screening throughout California, to ensure the requirements are being met. Clean Truck Check applies to in-state, out-of-state, and out-of-country heavy-duty vehicles operating in California. Beginning in 2024, all vehicles subject to CTC were required to register in the CTC reporting system and pay their compliance fee. The table below reports the number of vehicles screened by CARBs emissions screening system in 2024 and the number of vehicles that registered and paid their fees in 2024. In subsequent years, we will report on vehicles that completed their periodic testing in addition to those that registered and paid fees as the periodic testing requirements of CTC did not begin until January 1st, 2025.