What is Clean Truck Check? 

It is a regulation to test heavy-duty vehicles’ emissions control systems for proper operation. Clean Truck Check applies to nearly all diesel and alternative fuel heavy-duty vehicles with a gross vehicle weight rating (GVWR) over 14,000 pounds that operate on California public roads and highways even if they are not registered in California. This includes public vehicles (federal, state, and local government); motorcoaches; transit, shuttle and school buses; hybrid vehicles; commercial vehicles; personal vehicles; California registered motorhomes; single vehicle fleets; and vehicles registered outside of California (not including motorhomes).

How often will my vehicle require a passing emissions compliance test? 

Almost all vehicles are subject to semi-annual testing.  Agricultural vehicles (that meet the definition) and California-registered motorhomes for recreational use or emergency occupancy will only be required to undergo testing once per year. 

Beginning October 2027, on-board diagnostics (OBD) equipped vehicles will be required to undergo testing four times per year.

When can I get my vehicle tested?

Passing Clean Truck Check test results may be submitted up to 90 days before a compliance deadline. Testing deadlines for each vehicle will be shown in your CTC-VIS account and a monthly account summary will be emailed at the beginning of each month listing the number of vehicles with a compliance deadline in the next 90 days and the number of any open enforcement actions. 

How must my vehicles be tested? 

The testing requirements depend on whether your vehicle/engine is equipped with OBD or not.

While most vehicles have an engine model year one year older than the vehicle model year, please refer to the vehicles emissions control label (ECL) on the engine to ensure you are performing the correct test for the vehicle. 

OBD-equipped vehicles (2013 and newer diesel engines and 2018 and newer alternative fuel engines) are required to undergo a scan of the engine’s OBD data using a California Air Resources Board (CARB) certified OBD testing device. 

Diesel non-OBD vehicles (2012 and older diesel engines) are required to complete a smoke opacity test and a visual inspection of the vehicle’s emissions control equipment, referred to in this program as the Vehicle Emissions Control Equipment Inspection. Alternative fuel non-OBD vehicles (2017 and older alternative fuel engines) are only required to complete the visual inspection and are not subject to the smoke opacity test requirement. 

Do I need to send/upload my test results to CARB Clean Truck Check?

No, your Clean Truck Check credentialed tester is responsible for sending the results to CARB. You may view your test results in your account. 

What are next steps if my vehicle does not pass the emissions compliance test? 

If a vehicle fails the emissions compliance test, the vehicle owner should complete any needed repairs to bring the vehicle back into compliance. The vehicle should be tested post-repair and pass the emissions compliance test before the deadline. 

If an OBD-equipped vehicle receives other types of results, such as "Not Ready", " Vehicle Not Applicable For OBD Testing", and "Invalid Test", the result will not be considered compliant. Please follow the instructions accompanying the test result and retest the vehicle. For example, if an OBD-equipped vehicle receives a "Not Ready" result during the initial emissions compliance testing, the message accompanying the test result will advise the vehicle owner to operate the vehicle further to meet the OBD Readiness Criteria before retesting. Please ensure that the vehicle passes the emissions compliance test before the compliance deadline. 

Where do I get additional Clean Truck Check information? 

For more information, visit Clean Truck Check (HD I/M). Fact sheets, videos, and other information on requirements and reporting are available. 

If I have additional questions, how do I contact CARB? 

Please email staff at hdim@arb.ca.gov.  

Registration holds may be due to not meeting the compliance requirements for the Clean Truck Check program. For information on that program, visit Clean Truck Check Overview.

The registration hold may also have been placed by CARB enforcement based on their authority to place registration holds due to noncompliance with any CARB regulation.

✔ CARB enforcement sends a non-compliance notification with instructions on how to contact CARB and address the issue with your vehicle. 

If your DMV registration paperwork states a Clean Truck Check or SB 210/Q212 hold reason, please contact HDIM@arb.ca.gov
If the DMV paperwork states a CARB non-compliant or SB 1/Q208 hold, please contact ARB 8666Diesel or the Hotline at 1-866-634-3735.

If your vehicle's model year is 2010 or older, it is possible that your vehicle does not comply with the Truck and Bus regulation and may be the reason you have a registration hold on your vehicle. If you have any questions regarding compliance with the Truck and Bus regulation, contact TRUCRS@arb.ca.gov or the Hotline at 1-866-634-3735.