California Air Resource Board Implementing Phase 2 Of Clean Truck Check Program

Nov 29, 2023

Clean Truck Check, formerly known as the Heavy-Duty Inspection and Maintenance Program, was approved by the California Air Resources Board (CARB) in 2021. The program ensures heavy-duty vehicles operating in California are well-maintained and repaired quickly when needed to reduce emissions and improve public health statewide, especially in disadvantaged communities disproportionately impacted by air pollution. It also provides a level playing field for the businesses that operate these vehicles as it applies to both in-state and out-of-state registered heavy-duty vehicles. The program includes nearly all non-gasoline vehicles with a gross vehicle weight rating over 14,000 pounds that operate in California. This includes public vehicles, non-gas powered California-registered motor homes, trucks, buses, personal vehicles, single vehicle fleets, and vehicles registered outside of California (except for out-of-state motor homes which are specifically exempted).

Clean Truck Check is being implemented in three phases. Phase 1 began January 1, 2023. This initial phase began with the deployment of Remote Emissions Monitoring Devices (REMD). REMDs monitor the exhaust emissions of passing heavy-duty vehicles and flag potential high emitters that may receive a Notice to Submit to Testing (NST). NST’s require vehicle owners to submit a passing compliance test to CARB after any necessary emissions-related repairs are made, within 30 days of receipt of the notice. Failure to comply and remedy emissions-related concerns could result in DMV registration holds and/or removal from the compliance database.

Phase 2 of the program began October 1, 2023. This phase requires all vehicle owners who are subject to the program to enter their vehicles in CARB’s Clean Truck Check database and pay an initial annual compliance fee of $30 dollars per vehicle by December 31, 2023. Starting January 2024, all trucks driving in California will need proof of compliance to continue operating in the state. Operating in California without registration in the compliance database could result in violations from CARB and/or the California Highway Patrol.

Phase 3 of Clean Truck Check requires heavy-duty vehicle owners to conduct periodic emissions testing on their vehicle. This is similar to California’s Smog Check program for cars. Periodic testing begins in 2024 and applies to all compliance deadlines after July 1, 2024. Compliant tests may be submitted as early as April 2024. Periodic testing initially will be required twice per year for nearly all vehicles in the program. Agricultural vehicles and California-registered motor homes are required to test once annually. Testing requirements vary based on whether the vehicle is equipped with OnBoard Diagnostics (OBD). For California-registered vehicles, the compliance testing deadlines are linked to each vehicle’s DMV registration expiration/renewal date. For vehicles registered outside of California and for vehicles exempt from DMV registration requirements, compliance deadlines are based on the last number of a vehicle’s VIN. Passing test results may be submitted up to 90 days before a compliance deadline. Testing should be performed in a timely manner to avoid penalties and possible DMV registration holds.

For further information about the Clean Truck Check program, please visit the CARB website at: or view CARB'S Q&A: Clean Truck Check Requirements.