From
http://www.epa.gov/obd/warranties.htm#a
A. PERFORMANCE WARRANTY
The Performance Warranty covers repairs which are required during the first 2 years or 24,000 miles of vehicle use because the vehicle failed an emission test. Specified major emission control components are covered for the first 8 years or 80,000 miles. 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.
During the first 2 years/24,000 miles, the Performance Warranty covers any repair or adjustment which is necessary to make your vehicle pass an approved, locally-required emission test and as long as your vehicle has not exceeded the warranty time or mileage limitations and has been properly maintained according to the manufacturer's specifications.
B. DESIGN AND DEFECT WARRANTY
The Design and Defect Warranty covers repair of emission related parts which become defective during the warranty period. The Design and Defect warranty for model year 1995 and newer light-duty cars and trucks is outlined below:
Design and Defect Warranty Coverage for 1995 and newer light-duty vehicles:
Emission control and emission related parts are covered for the first 2 years or 24,000 miles of vehicle use; and
Specified major emission control components are covered for the first 8 years or 80,000 miles of vehicle use.
According to federal law, an emission control or emission related part, or a specified major emission control component, that fails because of a defect in materials or workmanship, must be repaired or replaced by the vehicle manufacturer free of charge as long as the vehicle has not exceeded the warranty time or mileage limitations for the failed part.
Design and Defect Warranty coverage may vary depending on the type of vehicle you have (e.g., heavy-duty trucks, motorcycles or recreational vehicles have different time and mileage requirements). To determine the length of warranty coverage that applies to your vehicle, look for the emissions warranty information in your owner's manual or warranty booklet. If you own a California vehicle, you may be entitled to additional warranty coverage.
The owner's manual or warranty booklet will also provide you with guidance on the procedures for obtaining warranty coverage. If you have questions about the emissions warranties on your vehicle or need help in filing a warranty claim, contact your local car dealer or the manufacturer's zone or regional representative listed in your owner's manual or warranty booklet.
What Emission Control and Emission Related Parts Are Covered by The Design and Defect Warranty?
An emission control part is any part installed with the primary purpose of controlling emissions. An emission related part is any part that has an effect on emissions. Listed below are some examples of parts or systems which fall under these definitions. A more complete list can be found in your owner's manual/warranty booklet. If any of the parts listed below fail to function or function improperly because of a defect in materials or workmanship, causing your vehicle to exceed federal emission standards, they should be repaired or replaced under the emissions warranty if your vehicle is less than 2 years old and has been driven less than 24,000 miles. One manufacturer may use more parts than another, so the following list is not complete for all vehicles.
EMISSION CONTROL PARTS
Exhaust Gas Conversion Systems: oxygen sensor, thermal reactor, catalytic converter, dual-walled exhaust pipe
Exhaust Gas Recirculation System: EGR valve, thermal vacuum switch, EGR solenoid, EGR spacer plate, EGR backpressure transducer, sensor and switches used to control EGR flow
Evaporative Emission Control System: purge valve, fuel filler cap, purge solenoid, vapor storage canister, and filter
Positive Crankcase Ventilation (PCV) System: PCV valve, PCV solenoid
Air Injection System: Air pump diverter, bypass, or gulp valve, reed valve, anti-backfire or deceleration valve
Early Fuel Evaporative (EFE) System: EFE valve, thermal vacuum switch, heat riser valve
Fuel Metering System: electronic control module (unit) or EFI air flow meter, computer command module or mixture control unit, deceleration controls, electronic choke, fuel injectors, fuel injection units and fuel altitude compensator sensor, bars or rails for EFI or TBI systems, mixture settings on sealed fuel mixture control solenoid, diaphragm or other systems, fuel metering components that achieve closed/other feedback control sensors/loop operation switches and valves
Air Induction System: thermostatically controlled air cleaner, air box
Ignition Systems: electronic spark advance timing advance/retard systems, high energy electronic ignition
Miscellaneous Parts: hoses, gaskets, brackets, clamps, and other accessories used in the above systems
EMISSION RELATED PARTS
These are examples of other parts of your vehicle which have a primary purpose other than emissions control but which nevertheless have significant effects on your vehicle's emissions. If any of these parts fail to function or function improperly, your vehicle's emissions may exceed federal standards. Therefore, when any of the parts of the following systems are defective in materials or workmanship and have failed in a way that would be likely to cause your vehicle's emissions to exceed federal standards, they should be repaired or replaced under the emissions warranty:
Fuel Injection System: fuel distributor
Air Induction System: turbocharger, intake manifold
Exhaust System: exhaust manifold
Ignition System: distributor, spark plugs, ignition wires and coil
Miscellaneous Parts: hoses, gaskets, brackets, clamps, and other accessories used in the above systems.
What Are Specified Major Emission Control Components?
There are three specified major emission control components, covered for the first 8 years or 80,000 miles of vehicle use on 1995 and newer vehicles:
Catalytic converters.
The electronic emissions control unit or computer (ECU).
The onboard emissions diagnostic device or computer (OBD).
Catalytic converters are critical emission control components that have been installed on most cars and trucks manufactured since 1975. Since engines don't burn fuel completely during the combustion process, the exhaust contains a significant amount of harmful pollutants such as carbon monoxide, hydrocarbons, and oxides of nitrogen. The catalytic converter aids the conversion of these pollutants to less harmful substances such as carbon dioxide, water vapor, nitrogen, and oxygen before the exhaust is expelled into the environment.
The electronic emissions control unit or computer monitors certain powertrain functions and controls various operating parameters to help the vehicle run efficiently and with the lowest possible emissions. Ignition, transmission function, air injection, exhaust gas recirculation (EGR), engine operating temperature and fuel system parameters are some of the systems monitored and/or controlled by the electronic emissions control unit.
The onboard emissions diagnostic device monitors the operation of a vehicle's emission control system and alerts the driver with a dashboard light when malfunctions occur. The system will record where the problem is occurring and assist automotive technicians in diagnosing and repairing emission control malfunctions. Since some emission control malfunctions do not have an adverse effect on vehicle performance, they can go undetected by the driver for quite some time. The onboard diagnostic device will help catch malfunctions early, preventing a significant output of harmful exhaust emissions from your vehicle, and possibly in time to be covered by the emissions control warranty. Often this "device" is part of the electronic control unit mentioned above.
In the future, there may be other parts or components that qualify for this coverage. Check your owner's manual or warranty book for possible additional coverage.
How Long Do the Emissions Warranties Apply to Individual Parts of My Vehicle?
For 1995 and newer model year vehicles, emission control and emission related parts are warranted for the first 2 years or 24,000 miles of vehicle use. Specified major emission-control components are warranted for the first 8 years or 80,000 miles of vehicle use.
Parts with a stated replacement interval, such as, "replace at 15,000 miles or 12 months," are warranted up to the first replacement point only.