How to Tell if a Catalytic Converter is OEM

[MichaelLynn]

Place your hand near the exhaust pipe outlet to feel the exhaust flow. If the exhaust volume is significantly less than other vehicles at the same throttle opening. Another method is to open the air filter, remove the filter element, and check for exhaust backflow during rapid acceleration. If backflow occurs, it indicates the catalytic converter is not OEM.

[McAlyssa]

I got burned in the used car market before, so now I always check the shell details first when inspecting a catalytic converter. OEM welds are exceptionally even with clean edge finishing, and the seal bears the vehicle's unique steel stamp. Aftermarket units often have rough seams and lighter-colored screws. The difference is even more obvious when opened up – OEM substrates have honeycomb channels aligned as precisely as printed text, while replacements are usually crooked. Last time I tested with a magnet – the OEM shell didn't stick (stainless steel), but knockoffs attracted it immediately. Oh, and some premium car converters now come with factory stickers – peel them to reveal anti-counterfeit laser codes visible under UV light. If you see screw marks or bluish weld spots, it's likely been swapped out.