Clearing the air: Which California truck emission rules are still in play?

Congress removed some vehicle emission rules in California, but not all. This has left many truck drivers unsure about the rules for driving in the Golden State.

In June, President Donald Trump signed off on resolutions that killed several California vehicle emission rules. Advanced Clean Trucks and the Omnibus Low NOx regulation were among them. However, the Clean Truck Check program was not affected.

Since then, the Owner-Operator Independent Drivers Association has heard from truck drivers asking if they can drive their older trucks in California like before. The short answer: No.

The Advanced Clean Trucks rule required 7% of truck manufacturers’ Class 7-8 truck sales for model year 2025 to be zero-direct-emission trucks. That percentage would rise each year until 2032, when 40% of sales must be zero-emission trucks.

That rule, which was adopted by 10 other states, caused significant issues. Some manufacturers required dealers to sell one battery-electric truck before they could order 13 diesel trucks. Since no one wanted an electric truck, dealerships could not order or sell diesel trucks. The problem was expected to worsen as sales requirements became stricter.

Now that Advanced Clean Trucks has been reversed, truckers, fleets and dealerships in California may not be held to those standards. Manufacturers did strike a deal with the state to adhere to those rules anyway. However, that agreement is in limbo and is being challenged in court.

The Omnibus rule set stricter emission standards for truck engines. While Advanced Clean Trucks impacted manufacturers like Daimler Truck, Paccar and Volvo, the Omnibus rule affected engine makers like Cummins. Those challenges are also in limbo.

Those are the only two California truck emission rules that were struck down by Congress. Everything else remains in play, including the Clean Truck Check program.

Approved by the California Air Resources Board (CARB) in 2021, Clean Truck Check requires all diesel and alternative fuel trucks over 14,000 pounds operating in California to pass an emission test.

The rule also requires each truck operating in California to register with the Clean Truck Check Inspection System (CTC-VIS) and pay a $31.18 compliance fee. That fee is adjusted to inflation each year.

Clean Truck Check applies to all diesel trucks in California, no matter where they are registered. Each truck must pass an emission compliance test twice a year. Starting in October 2027, trucks with on-board diagnostic (OBD) systems must be tested four times a year. This includes nearly all trucks with engines from 2013 or newer.

Deadlines for tests and fees are based on registration dates for California trucks and VINs for out-of-state trucks (bolded dates indicate fee deadlines):

Clean Truck Check did not need federal approval through an EPA waiver, unlike Advanced Clean Trucks and the Omnibus rule. Therefore, the emission-check rule will remain unless the state government repeals it, which is unlikely.

Essentially, barriers to manufacturing and purchasing diesel trucks in California are gone. However, owner-operators and fleets still need to report all trucks operating in the state and pass an emission test several times a year. That much has not changed. LL