Updated October 2026: Twice-a-year Clean Truck Check testing has been required since January 2025 and remains in force. Separately, CARB’s Advanced Clean Fleets rule for private and drayage fleets, discussed later in this article, was formally repealed on September 10, 2026. That repeal does not change your Clean Truck Check obligations.
The Clean Truck Check, California’s Heavy-Duty Inspection and Maintenance (HD I/M) program, is one of the state’s biggest moves to reduce air pollution from heavy-duty diesel vehicles. The California Air Resources Board (CARB) created it to curb emissions from vehicles weighing more than 14,000 pounds. While these trucks play a vital role in the state’s economy, their pollution, primarily nitrogen oxides (NOx) and fine particulate matter (PM 2.5), has been a persistent issue for California’s air quality.
What the Clean Truck Check requires
The program makes sure heavy-duty vehicles are regularly tested so that problems with emissions control systems, such as diesel particulate filters and selective catalytic reduction systems, are found and repaired quickly. Here is what applies in 2026:
- Who: nearly all diesel, alternative-fuel, and hybrid vehicles over 14,000 pounds GVWR that operate in California, including out-of-state trucks. Battery-electric and hydrogen fuel-cell vehicles are exempt.
- Register: every vehicle must be reported in CARB’s CTC-VIS online system.
- Pay: an annual compliance fee of $32.13 per vehicle in 2026, rising to $33.12 in 2027.
- Test: twice a year for most trucks, performed by a credentialed tester with results sent to CARB. Motorhomes and agricultural vehicles test once a year.
- Coming next: starting in October 2027, trucks subject to OBD-based testing (most newer trucks) move to four tests a year.
- Consequences: missing a test or fee can lead to a DMV registration hold, fines, and out-of-service orders.
CARB estimates that once fully implemented by 2037, the program will cut NOx emissions by 81 tons per day and PM emissions by 0.7 tons per day, and save more than 7,500 lives by reducing pollution-related illness. A 2026 bill (SB 1064) that would have cut testing to once a year for low-use trucks with 2012 or older engines was vetoed in September 2026, so the twice-a-year schedule stands.
The Advanced Clean Fleets fight, and how it ended
When this article was first published in 2024, the bigger controversy was CARB’s Advanced Clean Fleets (ACF) rule. It required drayage fleets, government fleets, and so-called high-priority fleets to switch to zero-emission trucks on a phased timeline. The trucking industry, truck equipment makers, and parts suppliers warned of enormous costs.
Industry associations, including the Specialty Equipment Market Association (SEMA) and the National Truck Equipment Association (NTEA), sued in October 2024. They argued the rule exceeded CARB’s authority, ignored specialized vehicles like utility trucks, emergency vehicles, and snowplows that are poorly suited to battery-electric power, and discriminated against out-of-state companies. A fleet with 49 trucks in another state and only one in California, for example, could still be covered. Seventeen states brought their own lawsuit as well.
The pressure worked. CARB withdrew its request for the federal waiver it needed to enforce the rule on private fleets and stopped enforcing the high-priority and drayage requirements. Under settlements with NTEA and SEMA and with the 17 states, CARB’s board voted in 2025 to repeal those requirements. The repeal took effect on September 10, 2026, after California’s Office of Administrative Law approved it. Only state and local government fleets remain covered, and they were given extra time to comply.
What it means for San Diego truck owners
For private fleets and owner-operators, the zero-emission purchase mandate is gone, which removes a huge cost hanging over the industry. But the Clean Truck Check is a separate program and is fully enforced. Keeping your emissions system healthy, staying ahead of your testing dates, and fixing problems before a test is the best way to avoid failed tests, registration holds, and lost work days.
Official information and sources
Need commercial truck repair or a Clean Truck Check in San Diego? Kearny Mesa Truck Center has kept San Diego trucks on the road since 1970. Open Monday to Friday, 8am to 5pm, at 5624 Kearny Villa Rd.