Clean Truck Check is a California Air Resources Board (CARB) compliance program designed to ensure heavy-duty diesel vehicles meet emissions standards while operating on California roads. The program requires periodic emissions checks for certain diesel trucks and fleets, helping reduce air pollution and improve air quality across the state.
Why Clean Truck Check Exists
California has some of the strictest air quality regulations in the United States. The Clean Truck Check program (officially the Heavy-Duty Inspection and Maintenance, or HD I/M, program) was created to:
- Reduce harmful diesel emissions
- Identify high-emitting vehicles
- Improve air quality in major metropolitan areas
- Ensure fleet compliance with CARB regulations
Who Needs a Clean Truck Check?
You may need Clean Truck Check compliance if you operate:
- Heavy-duty diesel trucks over 14,000 lbs GVWR
- Commercial fleet vehicles operating in California
- Out-of-state trucks entering California regularly
- Logistics, delivery, or construction fleets
- Diesel RVs and motorhomes over 14,000 lbs
Not sure if your vehicle qualifies? Read our 2026 CARB requirements guide for the full breakdown, or if you own a motorhome see our diesel RV testing service.
How the Clean Truck Check Process Works
The process typically includes:
- Vehicle identification and VIN verification
- On-board diagnostics (OBD) or emissions testing
- Reporting results to CARB systems
- Compliance confirmation or repair requirement if needed
The type of test your vehicle needs depends on its engine model year. We cover this in detail in Clean Truck Check vs smog check.
Mobile Clean Truck Check Services
Mobile testing allows fleets to stay compliant without visiting a testing station. A certified technician comes directly to your yard, depot, or job site — reducing downtime and keeping fleet operations moving efficiently. See how our mobile service works.
Get Help With Compliance
If you operate commercial vehicles in California, staying compliant with Clean Truck Check requirements is essential to avoid penalties and operational delays. Learn what's at stake in our guide to penalties and fines, or schedule mobile testing today.