If you're operating a heavy-duty truck in California, you've likely heard about the CARB Clean Truck Check (HD I/M)—but what exactly is it, and why does it matter?
Let’s break down what the Clean Truck Check is for, why CARB created it, and what it means for diesel and heavy-duty vehicle operators across the state.
The Purpose of the Clean Truck Check
The Clean Truck Check program is California’s answer to rising pollution from heavy-duty trucks. It’s designed to reduce harmful emissions from diesel vehicles and ensure that trucks operating in the state meet emissions standards throughout their lifespan, not just when they leave the factory.
Unlike traditional smog checks or opacity testing, Clean Truck Check focuses on real-world emissions performance—helping CARB identify and flag high-emitting vehicles before they create lasting environmental and public health problems.
Why Did CARB Create the Clean Truck Check Program?
No, it's not just to make your life harder. CARB (California Air Resources Board) developed the Clean Truck Check to:
- Catch vehicles with failing emissions systems
- Monitor On-Board Diagnostics (OBD) in real time
- Reduce exposure to nitrogen oxides (NOx) and particulate matter (PM2.5)
- Prevent trucks from bypassing emissions rules through loopholes
- Increase enforcement of vehicles operating in California, whether based in-state or not
The program is also designed to hold all truck operators accountable, including those from out of state who do business in California.
How It Works: On-Board Monitoring & Periodic Testing
The Clean Truck Check combines:
- Vehicle registration and compliance tracking via the CTC-VIS portal
- Periodic emissions testing (semi-annual now, moving to quarterly for newer trucks)
- Real-time data uploads from CARB-credentialed testers
- Automated enforcement through registration holds and inspection programs
If your vehicle fails to test, doesn’t register, or shows emission system errors—you may be flagged as non-compliant, even if the truck appears to run normally.
Who Does It Apply To?
The Clean Truck Check applies to most:
- Diesel and alternative fuel vehicles over 14,000 lbs GVWR
- Trucks with 2013 and newer engines equipped with OBD systems
- Older trucks requiring smoke opacity testing
- In-state and out-of-state vehicles operating in California
This includes commercial fleets, rentals, contractors, motorhomes, and government vehicles.
What Are the Penalties for Non-Compliance?
Failure to comply with the Clean Truck Check can result in:
- DMV registration holds
- Inspection citations and fines
- Being denied access to freight facilities, ports, or job sites
- Risk to your business if you rely on California routes
The Bottom Line
The CARB Clean Truck Check exists to keep California’s air clean—and to ensure that diesel trucks are emissions-compliant not just once, but all the time.
If you operate trucks in California, it’s your responsibility to register in the CTC-VIS system, stay on schedule for testing, and keep your vehicles compliant. Not sure where to start?
FleetFox can help with mobile testing that’s fast, certified, and CARB-compliant—no shop visit needed.
