In-Use Compliance Program

This page last reviewed January 24, 2012



The ARB is currently conducting two separate ongoing in-use vehicle test programs, the In-Use Compliance Program and the In-Use Vehicle Surveillance Program. Each of these programs is similar in which vehicles are borrowed from the public and tested for exhaust and evaporative emissions at the ARB's Haagen-Smit Laboratory in El Monte. However, the data generated from these programs are utilized for different purposes.

The ARB's In-Use Compliance Program is a key strategy to aid California in meeting ambient air quality standards. The goal of this program is to ensure that manufacturers' vehicles meet emissions standards throughout their useful lives. To accomplish this task, the ARB seeks a limited sample of vehicles from a given test group or engine family and duplicates the manufacturers' vehicle emissions certification tests. The vehicles are procured, restored to the manufacturers' specifications and tested in accordance with the Code of Federal Regulations. ARB and the manufacturers' representatives are present to oversee all aspects of the test program. Should a noncompliance situation occur within a given engine family, the ARB will work with the manufacturer to correct the problem on all affected vehicles. The corrective action is usually in the form of a statewide recall in which the manufacturer will notify all affected vehicle owners and state when and where to seek the recall repair. The cost of the repair and service is free to the vehicle owner.

The primary objective of the ARB's In-Use Vehicle Surveillance Program is to determine a fleet "snapshot" of baseline emissions for the mobile source emissions inventory. Secondary objectives include the evaluation of present and future emission control programs. ARB's current programs include:      

  1. Evaluating the Cost Effectiveness of the Smog Check Program

  2. Gathering Information on Deterioration Rates of Emission Control Equipment for In-Use Vehicles

  3. Evaluating Evaporative Emissions

  4. Gathering Chemical by Chemical (Speciated) Exhaust and Evaporative Profiles for In-Use Vehicles

  5. Evaluating Experimental Vehicle Test Cycles

Information About Testing Your Vehicle

Contact Information

For more information, please contact ARB's Public Information Helpline at (800) 242-4450.


Engine Family - A grouping of vehicles with similar engine displacements, emission control systems and certification standards.