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About Your Corvette's Catalytic Converter

This critical emissions component is governed by Federal law.


Catalytic Converter

The Catalytic Converter is a web of reactive metals that help reduce emissions as exhaust gasses pass through the device.

Photo courtesy of Romanm

The catalytic converter has been the cornerstone of automotive emission controls for the past 35 years. Controlling emissions from street cars is an important environmental concern. Cars today are far cleaner than in decades past, thanks in large part to improvements in catalyst technology. While extreme high-performance applications generally include removing one or more catalysts from the exhaust system, it is a violation of U.S. federal law to do so on a car registered for use on public roads. Moreover, removing the catalysts makes it harder, if not impossible, for your car to pass emissions testing. Keeping your catalyst is no bar to high performance. Your entire engine management system is designed to work with the catalyst and provide good performance.

Here is an excellent Q&A on the subject of catalytic converters and the legal issues with upgrading your exhaust.

What is a catalytic converter?

The catalytic converter is a muffler-type device that uses a ceramic or stainless steel alloy web that holds reactive catalyzing material (usually palladium or rhodium). When the exhaust gases pass through the catalytic converter and heat up the catalyst, a chemical reaction occurs that helps change carbon monoxide to carbon dioxide, and helps to burn off any unburned hydrocarbons that remain in the exhaust stream before it exits your car.

How do I know if I need to replace my catalytic converter?

Your catalytic converter should last well over 100,000 miles in a Corvette made in the last 30 years or so. Earlier models may need replacement sooner. You can kill a catalyst by using leaded gas in your car - which was a problem until leaded gas disappeared entirely from the market. You will know your catalyst needs replacing because your car will lose power and your emissions will be too high.

When can I legally install an aftermarket catalytic converter in my Corvette?

Generally, there are only 3 situations when you can install an aftermarket converter. They are:

  1. If the converter is missing from the vehicle when brought in for exhaust system repair.

  2. If a State or local inspection program has determined the existing converter has been lead poisoned, damaged, or otherwise needs replacement.

  3. If the vehicle is more than 5 years old or has more than 50,000 miles (8 years/80,000 miles for 1995 and newer vehicles ) and a legitimate need for replacement has been established and appropriately documented (such as a plugged converter or unrepairable exhaust leaks).

What should Corvette owners know about buying converters for their cars?

First and most importantly, the original converter on a Corvette was designed to last the life of the vehicle if it is properly used and maintained, and is fully warranted by Chevrolet to last for at least 5 years or 50,000 miles (8 years or 80,000 miles on 1995 and newer), whichever comes first. See your warranty booklet for more information.

It is illegal to remove a functional catalytic converter even to replace it with a newer or better one.

It is illegal to tamper with emission control devices. The Anti-tampering Law applies to individuals as well as to businesses. Individuals may be fined as much as $2,500 for each vehicle tampered with, and businesses are subject to fines of up to $25,000.

How can I tell if an aftermarket converter meets EPA requirements?

Any converter that meets EPA requirements and is an acceptable, legal substitute must be properly labeled and warranted to meet Federal durability and performance standards.

Manufacturers of new aftermarket converters are required to have a 5 year/50,000 mile warranty on the converter shell and end pipes. They are also required to be warranted to meet EPA's emission performance standards for 25,000 miles when the vehicle is properly used and maintained. All manufacturers who meet the requirements also must state that fact in writing and obtain an individual manufacturers EPA code. Usually this is stated in the warranty information or application catalog.

EPA requires that a new, legal replacement catalytic converter must be properly labeled. Required labels on the converters will have a series of letters and numbers in the following format:


Here's what that label means:

N - indicates a new converter
XX - is the manufacturer's code issued by EPA
YYYY - is usually a numerical designation of the vehicle application or part number
ZZZZ - is the month and year of manufacture (i.e., "0187" for January 1987)

Note that converters manufactured for sale in California may have the letters "CA" in place of the "N" or "U". Since California standards are more stringent than EPA's, these converters will also meet EPA requirements. If your new catalytic converter does not have this label it may not be a legal replacement part for your application, placing you in violation of federal law.

What are the requirements for businesses installing an aftermarket converter? Besides installing aftermarket converters only in the 3 situations outlined above, other requirements and restrictions also apply. These include completely documenting the need for converter replacement, properly installing the correct one on the vehicle, and informing the customer of his rights and certain restrictions.

What may happen if I don't use the correct converter?

Your Corvette's performance can also be affected by the use of the wrong converter and, in some severe cases, converter or engine overheating could occur, resulting in unsafe operation and possibly engine damage. The conditions or even simply the use of the wrong part on a vehicle may allow the converter manufacturer to not honor the 25,000 mile of the 5 year/50,000 mile warranty.

Furthermore, it is illegal to tamper with emission control devices. The Antitampering Law applies to individuals as well as to businesses. Individuals may be fined as much as $2,500 for each vehicle tampered with, and businesses are subject to fines of up to $25,000.

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