Engine Family Number & Test Group For Catalytic Converter

Because vehicle manufacturers often use the same engine sizes in different models of the vehicles they produce the EPA has required engines be classified with an Engine Family Number. You may often encounter different model vehicles equipped with engines from the same engine family, or visa-versa... same model vehicle equipped with an engine from a different engine family. The engine family number (EFN) allows vehicle owners, aftermarket parts manufacturers, and automotive repair centers to identify an engine's exact specifications and its emissions control equipment. In this particular case, we're trying to find an aftermarket catalytic converter which is designed for use with your vehicle's particular engine family class. We must find a CAT which has been tested and approved for use specifically with your vehicle's  engine EFN.

As far as the testing and approval process for aftermarket catalytic converters... the engine family number now becomes an identifier of a particular CAT seeking CARB approval. During this process, the EFN is used and referred to as a Test Group number. It's in fact the same EFN (no modification to the number) but because the catalytic converter is going through a test phase, the EFN of the engine which the CAT has been designed for is used as an identifier for the test and also as a reference for any vehicle owner seeking to purchase the CAT as a replacement. If an approved aftermarket catalytic converter test group number does not match a vehicle's engine family number, it may not be used in that vehicle as a replacement even if the component fits. An aftermarket CAT must posses a valid EO (executive order number) and must have been tested and approved for use with a specific engine family.

We would recommend contacting the State's Emissions Parts Hotline to get help locating an aftermarket catalytic converter for your vehicle. You may reach the states parts hotline at (800) 622-7733.