What Is the CARB Clean Truck Check Program? Complete Guide for California Truckers
California’s CARB Clean Truck Check program is one of the most significant heavy-duty vehicle emissions requirements in the country. If you operate a diesel truck, bus, or RV in California, here’s everything you need to know.
What is the CARB Clean Truck Check?
The CARB Clean Truck Check, officially called the Heavy-Duty Inspection and Maintenance (HD I/M) Program, is a mandatory periodic emissions compliance program administered by the California Air Resources Board (CARB). It requires most heavy-duty diesel and alternative fuel vehicles operating in California to undergo regular emissions inspections to ensure they are functioning within established environmental standards.
The program was developed as part of California’s broader effort to improve air quality across the state, with a particular focus on reducing harmful particulate matter and nitrogen oxide (NOx) emissions from heavy-duty diesel vehicles.
Who does it apply to?
The Clean Truck Check applies to nearly all diesel and alternative fuel heavy-duty vehicles with a Gross Vehicle Weight Rating (GVWR) of more than 14,000 pounds that operate on California public roads. This includes commercial trucks, delivery vehicles, buses, motor coaches, privately owned vehicles, and California-registered motorhomes and RVs.
Exemptions include gasoline-powered vehicles, zero-emission vehicles (ZEVs), military tactical vehicles, and most historical vehicles.
How does testing work?
Testing under the Clean Truck Check program varies depending on your vehicle’s engine model year.
For 2013 and newer engines, OBD (On-Board Diagnostics) periodic testing is required. A CARB-credentialed technician connects a state-approved diagnostic device to your vehicle’s OBD port and reads the emissions system status directly from the vehicle’s computer. This test is fast, accurate, and results upload to the CARB portal immediately upon completion.
For 2012 and older engines, OVI (Opacity and Visual Inspection) periodic testing is required. This involves a traditional smoke opacity measurement and a hands-on visual inspection of the engine’s emissions control components. OVI results take several business days to process after submission.
What happens if you miss a deadline?
If your vehicle misses its compliance testing deadline, CARB notifies the California DMV, which places a hold on your vehicle’s registration renewal. You cannot legally renew your registration until compliance testing is completed and results are submitted to CARB.
The fastest way to clear a DMV registration hold is mobile CARB testing. Our CARB-credentialed technicians serve Sacramento and all of Northern California. We come to your location, test on-site, and upload results immediately for OBD-equipped vehicles.
How often is testing required?
Testing frequency depends on your vehicle’s model year, engine type, and compliance history. The program requires periodic testing on a schedule determined by CARB. For current deadlines and testing schedules, visit cleantruckcheck.arb.ca.gov or call (916) 538-7777.
How to stay compliant
- Register your vehicle in the CARB Clean Truck Check portal
- Keep track of your testing deadlines
- Schedule testing before your deadline, not after a hold has been placed on your registration
- Use a CARB-credentialed tester and confirm results are uploaded to the portal after each test