CARB: Clean Truck Check

Scope

This regulation applies to vehicle owners that operate covered vehicles in California.

Regulatory citations

• Title 13, California Code of Regulations, Division 3, Chapter 3.7, Sections 2195 to 2199

Key definitions

• California Air Resources Board (CARB): The state agency in California charged with controlling air pollution.
• Compliance months: The months in which a vehicle’s annual registration fee and OBD downloads are due. The specific date the fees and downloads are due will be visible in the vehicle’s CTC-VIS data. For a California registered vehicle this will be the month the vehicle registration expires and six months later. Here is a table that shows this:

• Covered vehicle: A vehicle with a gross vehicle weight rating (GVWR) of 14,001 pounds or more that is powered by a non-gasoline engine (gasoline powered vehicles are covered under a separate regulation). Vehicles that are exempt from this regulation include:
  • Zero-emission vehicles
  • Military tactical vehicles
  • Emergency vehicles
  • Historical vehicles
  • New vehicles with engines certified to the most stringent optional, NOx standard (only during the first four years of Clean Truck Check implementation)
  • Motorhomes registered outside of California
  • Vehicles operating under an experimental permit
  • Vehicles operating in California under a five-day temporary pass

• Licensed tester: An individual that has completed the CARB Heavy Duty Inspection and Maintenance Tester Course, passed the final examination, and that has been issued a HD I/M Tester Identification Number by CARB. Licensed testers use CARB approved electronic OBD download devices or smoke opacity testers to verify the vehicle is meeting its emissions limits.
• Malfunction indicator lamp (MIL): The “check engine” light on the dashboard of the vehicle.
• Diagnostic trouble code: An electronic indication in the OBD data that there is a problem with the engine.
• Onboard diagnostics (OBD): An electronic system on the vehicle that tracks engine and vehicle performance, and emissions status.
• Warm-up cycle: The time from cold start until the vehicle comes up to operation temperature.
• Zero emissions vehicle (ZEV): A vehicle that CARB has certified as operating with zero emissions. Examples include battery-powered vehicles and vehicles powered by hydrogen fuel cells.

Summary of requirements

The Clean truck Check program (originally known as the Heavy-Duty Inspection and Maintenance regulation, or HD I/M regulation) requires all non-gasoline powered internal combustion engine (ICE) vehicles that operate in California with a GVWR of 14,001 pounds or more to be registered in CARB’s CTC-VIS database. Part of registering includes paying a per vehicle annual compliance fee ($30 per vehicle for 2023 and 2024).

If a vehicle that is not entered into the CTC-VIS database will start operating in California, the owner/operator of the vehicle must enter it into the CTC-VIS database and pay the fee before the vehicle operates in California.

Vehicle owners or operators must upload onboard diagnostic (OBD) downloads twice a year to CARB. The purpose of this test is to prove the vehicle is operating within its designed emissions parameters.

If the vehicle has a malfunction indicator lamp or an active trouble code related to emissions, the vehicle will not pass the test, and must be repaired.

Also, if the vehicle had a diagnostic trouble code that was reset prior to the test, the software the tester uses will verify that the vehicle has done at least five warmup cycles without the trouble code returning. If the trouble code was a permanent diagnostic trouble code, the vehicle must have undergone at least 15 warmup cycles without the trouble code returning to pass the test.

If the vehicle does not have an acceptable OBD system, such as the vehicle has an engine older than model year 2013, the tester must do a smoke opacity test and visual inspection of all emissions components.

The OBD or smoke opacity test must be done by a CARB licensed HD I/M tester. Becoming a licensed tester involves taking a CARB training class, passing the final exam, and acquiring the approved equipment.

The OBD/smoke opacity test submission and fee due dates are based on the vehicle's plate expiration date (if registered/plated in California) or the last digit of the VIN (if registered/plated in another state).