If you operate a diesel truck or heavy-duty vehicle in California, you may be required to meet strict emissions testing rules under CARB’s Clean Truck Check (HD I/M) program. But who exactly is required to comply—and which vehicles are included?
In this post, we’ll break down what trucks need to be CARB compliant, what exemptions exist, and how to avoid costly fines and DMV registration holds.
Who Does CARB Clean Truck Check Apply To?
The Clean Truck Check program applies to most diesel and alternative-fuel trucks with a gross vehicle weight rating (GVWR) over 14,000 pounds that operate on public roads in California.
This includes:
- California-based commercial trucks
- Out-of-state trucks that enter California
- Government and municipal fleets
- Rental trucks and mobile service vehicles
- Motorhomes with diesel engines
Vehicle Types That Must Be CARB Compliant
If your vehicle falls into one of these categories, it likely must comply with Clean Truck Check testing and reporting:
- Semi-trucks and tractors
- Box trucks and dry vans
- Refrigerated trucks (reefers)
- Flatbeds and tankers
- Dump trucks and roll-off trucks
- Concrete mixers and water tenders
- Tow trucks (light, medium, and heavy-duty)
- Side loaders, front loaders, rear loaders (waste trucks)
- Catering and production trucks
- Motorhomes with diesel engines (over 14,000 lbs GVWR)
All these vehicles must be registered in the Clean Truck Check Vehicle Inspection System (CTC-VIS) and tested regularly. Check our Step-By-Step Instructions for Registering Your Vehicle(s).
Out-of-State Trucks Must Comply Too
Even if your vehicle is registered outside California, you are still required to:
- Register your truck in the CTC-VIS portal
- Pay the $30 annual compliance fee
- Complete emissions testing through a CARB-credentialed provider
If you drive in California—even temporarily—you’re subject to these rules.
Exemptions: Which Vehicles Are Not Required to Comply?
The following vehicles may be exempt from Clean Truck Check:
- Gasoline-only vehicles
- Diesel vehicles under 14,000 lbs GVWR
- Zero-emission (ZEV) or electric trucks
- Dedicated off-road equipment not operated on public roads
- Certain agricultural vehicles may qualify for reduced testing
Even exempt vehicles may require documentation or registration to avoid penalties. Always confirm your status in the CTC-VIS system.
How to Know If Your Truck Is Subject to CARB Rules
CARB uses your vehicle’s VIN, engine model year, and fuel type to determine your testing requirements. After you register in CTC-VIS, you’ll see:
- Your vehicle’s compliance schedule
- When tests are due
- Your current emissions status
Don’t assume you’re exempt—check your status directly in CTC-VIS.
Final Note: If Your Truck Works in California, It Probably Needs Testing
California is the strictest state in the U.S. when it comes to emissions enforcement. If your diesel vehicle operates here—even part-time—you’re likely required to be CARB compliant.
FleetFox can help you confirm eligibility and provide mobile emissions testing that keeps you road-legal without taking trucks out of service.
