Catalytic Converters

Buying guide: Catalytic Converters

A catalytic converter converts the three regulated exhaust gases - carbon monoxide, unburned hydrocarbons and nitrogen oxides - into carbon dioxide, water vapour and nitrogen. When the original fails, the check engine light usually comes on with a P0420 or P0430 code, fuel economy drops, and the vehicle will not pass an emissions test in most states.

This category holds 11,022 converters covering model years 1964 through 2024. Ford, Chevrolet and Toyota make up the largest share of applications, followed by Dodge, Nissan, Honda, Hyundai, Mazda, Buick and Chrysler. Magnaflow supplies most of the range, with Walker, AP Exhaust, AB Catalytic and Eastern Catalytic covering the rest.

Direct-fit or universal is the first decision. Direct-fit units (6,717 listings) bolt to the factory flange and hanger points without cutting or welding, which is the right choice whenever the exhaust has not been modified. Universal units (712 listings) cost less and ship smaller, but you have to measure pipe diameter, choose an inlet and outlet configuration, and weld or clamp the converter in place.

California rules sit on top of that. If the vehicle is registered in California - or in New York, Maine, Colorado or any state that has adopted CARB standards - the converter has to carry an executive order number. About 2,195 listings here are marked California or CARB compliant. Check that before ordering rather than after a failed inspection.

Two details worth confirming before you buy. The number stamped on the old converter should match the part number on the listing, and the engine size and drive type on the product page should match your VIN. Converters are built per engine configuration, so a listing for the same model year with a different engine will not fit even though the vehicle looks identical.