Vehicle manufacturers are required to design and build their vehicles to meet emission standards for the useful life of the vehicle specified by law. Under a federal law called the Clean Air Act, if the United States Environmental Protection Agency (EPA) determines that a substantial number of vehicles in a class or category do not meet emission standards in actual use even though they are properly maintained and used, EPA can require the manufacturer to recall and fix the affected vehicles.

EPA conducts emissions testing on randomly procured in-use vehicles at the National Vehicle and Fuels Emission Laboratory in Ann Arbor, Michigan. The vehicles are screened for proper use and maintenance, and then tested for emissions compliance in the laboratory. If problems are found, discussions begin with the manufacturer on possible remedies, which may include a recall of the affected vehicles.

Manufacturers are required to report certain defects they find to EPA if they affect emission-related parts. Many times the discovery of these defects leads to voluntary recalls or service campaigns. Manufacturers are also required to report to EPA all emission-related voluntary recalls.

Recalls and other remedies are usually conducted voluntarily by the manufacturer, although EPA has the authority to order a manufacturer to recall and fix noncomplying vehicles. Most recalls are initiated voluntarily by manufacturers once a potential noncompliance is discovered. These voluntary actions could be influenced indirectly by the potential for EPA action. Some voluntary recalls are directly influenced via EPA in discussions with manufacturers.

More information on emissions recalls from the EPA:

• Current Calendar Year Emissions Recalls and Announcements
• Past Emissions Recalls
• Vehicle Standards and Regulations: Air Pollution