CARB Clean Truck Check Program Deadline Delayed to Jan 31, 2024

MTA member carriers whose trucks travel routes in California should note that the CARB’s Clean Truck Check program has extended the deadline to register non-California plated trucks in the program’s online database to January 31, 2024. The original deadline was at midnight on December 31, 2023.


Under California’s Heavy Duty Vehicle Inspection and Maintenance program (HD I/M), out-of-State owners of all heavy-duty vehicles that operate in California must do the following:

  1. Register each vehicle that operates in California in the Clean Truck Check Database
  2. Ensure that each vehicle is tested and that the test data is reported in the Clean Truck Check Database, as periodically required by the program.


What follows is a summary of the steps that affected carriers need to take, and links to more detailed information.



To access the online registration database, please visit There is a $30 fee to register each vehicle. Be sure to scroll down the page to the Registration and Login links. If a company fails to register an affected vehicle by the January 31 deadline, those vehicles will be considered non-compliant and may be subject to a Notice of Violation and financial penalties.

Details on the information required to be submitted to the database can be found at:


On Board Diagnostic (OBD) testing can be done on diesel trucks with a 2013 model year or later, because they have electronic interfaces that accept OBD devices. Trucks older than the 2013 model cannot use the data entry process for OBD test results. OBD-capable trucks are required to undergo a scan of the engine’s data using a CARB-validated OBD test device. The carrier needs to ensure that a CARB-approved testing device is used to obtain the data required by the Clean Truck Check reporting program. The following web page lists testing devices approved for the program by the State of California:

Testing compliance deadlines are based on the last number of a vehicle’s VIN, for vehicles registered outside of California, as shown below:

Last Number of VIN 0 1 2 3 4 5 6 7 8 9
Month Oct Nov Dec Jan Feb Mar Apr May Jun Jul

As noted by CARB, “an example for twice per year testing, if a vehicle’s VIN ends in 9, the first compliance test results would be due by the last day of July, and the second compliance test results would be due six months later by the last day of January. Passing HD I/M test results may be submitted up to 90 days before a compliance deadline.” Readers can use the following link to obtain more information on testing:

Test Frequency

OBD tests are required every six months. Starting in 2027, vehicles equipped with OBD will begin reporting quarterly. A high-emitting vehicle can still be flagged for testing in between the OBD tests if it happens to pass near a roadside emission monitoring device. If this is the case, the registered owner will receive a letter from CARB requiring a new OBD compliance test to be submitted within 30 calendar days.  Additional guidance on testing is available here:

If carriers have questions, there is an FAQ page here, including links to more information:


Carrier can also e-mail the Clean Truck Check (HD I/M) program at