Updated October 2026: Twice-a-year testing is now in full effect, the annual CARB fee has risen to $32.13 (and goes to $33.12 in 2027), and quarterly testing for most newer trucks is set to begin in October 2027. A 2026 bill to ease testing for older, low-use trucks was vetoed. Details below.
The California Air Resources Board (CARB) runs the Clean Truck Check program, often called the “Diesel Truck Check” and formally known as the Heavy-Duty Inspection and Maintenance (HD I/M) Regulation, to reduce emissions from heavy-duty vehicles. While the goal is cleaner air, the program has raised significant concerns within the trucking industry about its cost and its effect on day-to-day operations.
Who has to comply
The program covers nearly all diesel, alternative-fuel, and hybrid trucks, buses, and other vehicles with a gross vehicle weight rating (GVWR) over 14,000 pounds that operate in California. It applies to California-registered vehicles and to out-of-state trucks that drive on California roads, which casts a very wide compliance net. Battery-electric and hydrogen fuel-cell vehicles are exempt.
How the rollout happened
Roadside emissions monitoring began in January 2023, followed by vehicle registration in CARB’s Clean Truck Check Vehicle Inspection System (CTC-VIS) and annual fees. Periodic testing was originally planned for 2024, but CARB pushed the start to January 2025. Since then, most trucks have had to pass an emissions test twice a year, on a schedule tied to their DMV registration.
The operational and financial burden
Truck owners must register every vehicle in CTC-VIS, pay an annual compliance fee, and make sure each one passes its periodic tests. That means more paperwork and more downtime for inspections or repairs, which disrupts delivery schedules, raises operating costs, and cuts fleet efficiency.
The fee started at $30 per vehicle and has climbed every year since: it is $32.13 per vehicle in 2026 and rises to $33.12 starting in January 2027. That may sound minor, but for a large fleet it adds up quickly. If a vehicle fails, the repair bill can be far larger, particularly for older models where parts are hard to find or expensive. The burden falls hardest on small and medium-sized trucking businesses.
Non-compliance has real consequences. Vehicles that are not registered or have not passed testing can face DMV registration holds, fines, and out-of-service orders, and may be kept out of high-traffic areas like ports and railyards, which complicates logistics further.
Quarterly testing is next
Testing gets more frequent soon. Beginning in October 2027, vehicles subject to OBD-based testing, which is most newer trucks, will need to test four times a year instead of twice. That is more scheduling, more downtime, and more cost for every fleet, and it could discourage out-of-state carriers from operating in California, which might reduce competition and raise local transportation costs.
Relief bill vetoed in 2026
Industry groups have asked for grants, tax incentives, or a slower phase-in to help businesses adjust. In 2026, the Legislature passed SB 1064 by Sen. Megan Dahle, which would have limited testing to once a year for low-use, California-registered heavy-duty trucks with 2012 or older engines. The California Farm Bureau and others urged the governor to sign it, but the bill was vetoed in September 2026, so the existing testing schedule stays in place.
Our take
While the program seeks cleaner air, its implementation has created significant challenges for California’s trucking industry: lost efficiency, rising costs, and a shifting competitive landscape. These issues show the need for a balanced approach that weighs environmental benefits against the economic impact on an industry crucial to both the state’s and the nation’s economy. In the meantime, the best defense is a well-maintained emissions system and a testing plan that fits around your work schedule.
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.