The vehicle producers are obliged to design and develop their vehicles to meet emission standards for the useful life of the vehicle as mandated by the law. Under a federal law which is known as the Clean Air Act, if the US Environmental Protection Agency or EPA reveals that huge number of vehicles in a group or category do not meet the emission standards in concrete use  even if they are properly maintained, EPA can ask the manufacturer to withdraw and fix the concerned vehicles.

The EPA performs emissions testing on randomly purchased in-use vehicles at the National Vehicle and Fuels Emission Laboratory located in Ann Arbor, Michigan. The vehicles are inspected for correct use and maintenance, and then examined for emissions compliance. If there are problems, the discussions start with the manufacturer on potential solutions, including recalling the affected vehicles.

The manufacturers need to report some defects they discover to EPA if these affect the emission-related parts.  There are many times when knowing these defects result in voluntary recalls or service campaigns. Manufacturers are also asked to report to EPA all emission-associated recalls.

Recalls and other solutions are done voluntarily by the manufacturer, even if EPA has the right to order the manufacturer to recall and repair noncomplying vehicles.  Most of these recalls are done voluntarily by manufacturers when potential noncompliance is found. These voluntary actions could be manipulated indirectly by the potential for EPA action.  Some voluntary recalls are directly influenced through EPA in deliberations with the 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