CARB Clean Truck Check
Requirements Explained.

Clean Truck Check is the operating name for California's Heavy-Duty Inspection and Maintenance (HD I/M) program, created by Senate Bill 210 in 2019 and administered by the California Air Resources Board (CARB). It replaces the old Periodic Smoke Inspection Program (PSIP) with a modern, OBD-based inspection system tied directly to DMV registration.

Every subject vehicle is tracked in CTC-VIS — the Clean Truck Check Vehicle Inspection System — where compliance fees are paid and passing emissions tests are recorded.

Nearly all non-gasoline heavy-duty vehicles over 14,000 lbs GVWR operating on California roads must comply, including diesel, alternative fuel, and hybrid units. Out-of-state trucks operating in California are held to the same requirements as in-state trucks.

A limited set of exemptions exists — such as certain zero-emission vehicles, historical vehicles, and specific military and emergency vehicles — but the default assumption is that a heavy-duty diesel working California roads is subject to Clean Truck Check.

Reporting in CTC-VIS. Every subject vehicle must be registered in the CTC-VIS portal with accurate VIN, GVWR, and fleet information.

Annual compliance fee. An annual per-vehicle fee is owed to CARB through CTC-VIS. This fee is separate from DMV registration and separate from the cost of the emissions test itself.

Passing emissions test. Each subject vehicle must submit a passing emissions test on the CARB schedule. Today that's semi-annual (twice per year) for most subject vehicles.

The current cadence is semi-annual: two passing tests per year, tied to your compliance windows in CTC-VIS. A passing test can be submitted up to 90 days before the deadline, giving you a working buffer for repair-and-retest if a truck fails.

Starting October 2027, OBD-equipped vehicles move from semi-annual to quarterly testing under CARB's phased rollout, effectively doubling the testing volume for most modern trucks.

CARB can block DMV registration renewal for any vehicle that isn't compliant with Clean Truck Check — no sticker, no legal operation. Civil penalties for operating out of compliance reach up to $10,000 per vehicle per day.

CHP and CARB inspectors also check Clean Truck Check status at roadside inspections. A non-compliant truck can be placed out of service on the spot, in addition to citations issued to the operator and carrier.

The Clean Truck Check emissions test is performed on the vehicle using an OBD-based device — meaning it doesn't require a shop bay. A CARB-credentialed tester can bring the equipment directly to your yard, run the test at the truck, and submit the result to CTC-VIS the same day.

For fleets that would otherwise pull revenue units off route to visit a shop, mobile testing eliminates the downtime. See our homepage for the four-step process, or jump straight to a city we serve.