The Clean Air Act requires manufacturers of light-duty vehicles to provide two federal emission control warranties: (A) "Performance Warranty" and (B) "Design and Defect Warranty." These warranties are provided by the vehicle manufacturer and apply to used vehicles as well. The warranty period begins from the date of sale to the original owner.

The Performance Warranty covers repairs which are required during the first 2 years or 24,000 miles of vehicle use (whichever first occurs) because the vehicle failed an emission test. Specified major emission control components are covered for the first 8 years or 80,000 miles (whichever first occurs). The specified major emission control components only include the catalytic converters, the electronic emissions control unit or computer (ECU), and the onboard emissions diagnostic (OBD) device or computer. If you are a resident of an area with an Inspection and Maintenance (I/M) program that meets federal guidelines, you are eligible for this warranty protection provided that:

• Your car or light-duty truck fails an approved emissions test; and
• Your vehicle is less than 2 years old and has less than 24,000 miles (up to 8 years/80,000 miles for certain components); and
• Your state or local government requires that you repair the vehicle; and
• The test failure does not result from misuse of the vehicle or a failure to follow the manufacturers’ written maintenance instructions; and
• You present the vehicle to a warranty-authorized manufacturer representative, along with evidence of the emission test failure, during the warranty period.

The Design and Defect warranty covers repair of emission control or emission related parts which fail to function or function improperly because of a defect in materials or workmanship for 2 years or 24,000 miles (whichever first occurs), and the specified major emissions control components mentioned above for 8 years or 80,000 miles (whichever first occurs). The manufacturer can deny this warranty coverage if evidence shows that the emission component failure was caused by improper use or maintenance and not caused by a defect.

A list of these components and a description of the warranties (PDF) (10 pp, 697K, EPA-420-F-15-035, October 2015) is available on our web site. However, vehicle technology is constantly changing, therefore there may be emissions control components or emissions related components which do not appear on this list. A more complete list can be found in your owner's manual/warranty booklet. The specified major emissions control components, however, are specified in the Clean Air Act and are the only components subject to the 8 years/80,000 mile federal emissions warranty.

When you believe you have identified a defective part, or your vehicle fails an emission test, you should follow the procedures for making a warranty claim as identified by the manufacturer in your owner’s manual or warranty booklet. If you plan to have the manufacturer pay for a repair under either of the emissions warranties, you must take the vehicle to a facility authorized by the vehicle manufacturer for repair to give them the opportunity to diagnose and repair it. Note that if your regular repair facility is not authorized by the vehicle manufacturer, they are not obligated to advise you of parts that are covered under warranty. Before giving your automotive technician the “go ahead” to perform repairs, check your owner’s manual/warranty booklet for possible warranty coverage. Additional state laws may apply, so you might want to contact your state Department of Motor Vehicles to find out.