* All heavy duty vehicles weighing 14,000 lbs. or more and run on diesel, must be registered with CARB, through the CTC-VIS portal.

* Vehicle owners will pay a $30 annual compliance fee per vehicle. Fee is payable to CARB through the CTC-VIS portal.

* Vehicles that fall within the CARB mandate will be tested on a semi-annual basis.

* Testing due dates will coincide with the vehicles' registration due date or the last digit of the VIN number. CTC-VIS monthly email will alert vehicle owners of testing due dates.

* Vehicles with the MIL or Check Engine light activated, must have necessary repairs addressed in order to achieve a "passing" test result.

* Vehicles with recent repairs must go through a number of warm-up cycles, in order to be "Ready for testing". The number of warm-up cycles required varies between vehicles.

* OBD testing will be performed on engine models 2013 and newer. Engine models 2012 and older are subject to the Opacity and Visual Inspection test.

- For more in depth information on the Clean Truck Check Heavy Duty Maintenance and Inspection Program (HD I/M). Please visit the California Air Resource Board website at www.arb.ca.gov.