California Air Resources Board

CARB's In-Use Compliance Programs are a key strategy to aid California in meeting ambient air quality standards. The Heavy Duty In-Use Compliance section is responsible for multiple programs including: Heavy-Duty In-Use Compliance Program (HDIUC), Off-Road In-Use Compliance (ORIUC), and the Manufacturer run Heavy-Duty In-Use Testing Program (HDIUT). One of the main goals of these programs is to ensure that heavy-duty vehicles/engines meet required emissions standards throughout their useful lives.

To support this program, CARB tests a limited sample of vehicles from a given test group or engine family and duplicates the vehicle emissions certification tests. The vehicles are procured, restored to the manufacturer’s specifications, if applicable, and tested in accordance with the California Code of Regulations (CCR) and the Code of Federal Regulations (CFR). 

CARB and manufacturer representatives work together during all aspects of each test program. Should a noncompliance situation occur the CARB will work with the manufacturer to correct the problem on all affected vehicles. The corrective action, typically a manufacturer based emission recall campaign, will correct the non-compliance at no cost to the vehicle owner. The CARB In-use Compliance Programs have successfully influenced the recall of over 1 million vehicles resulting in cleaner air for California.