What is Clean Truck Check? It is a regulation to test heavy-duty vehicles’ emissions control systems for proper operation. Clean Truck Check applies to nearly all diesel and alternative fuel heavy-duty vehicles with a gross vehicle weight rating (GVWR) over 14,000 pounds that operate on California public roads. This includes both in-state and out-of-state vehicles, as well as public vehicles (federal, state, and local government); motorcoaches; transit, shuttle and school buses; hybrid vehicles; commercial vehicles; personal vehicles; California registered motorhomes; single vehicle fleets; and vehicles registered outside of California (not including motorhomes). At S.E. Smith and Sons, we have certified technicians who can come to you or perform an inspection at our facility. Trust us to take care of you rig and have you on the road with assurance.