Is your catalytic converter bad?

3D illustration

We get several customers a week coming in asking to replace their catalytic converters, as they were told they were bad and needed replaced. Not only is this expensive, especially if you require a direct fit cat but it could also be unnecessary.

You’re pulling a P0420 code? - This is a common code that can will pull from all makes and models post 1996 and newer. Before we talk about replacing a catalytic converter we check each sensor to make sure they are in working order, we check for exhaust leaks, check the cat itself. We run a live data feed at idle, and do a heat check see if there is a 100 degree difference on the cats.

Come visit us before you replace your cats and we will check them for you.

Possible causes for the code:

  • Leaded fuel was used where unleaded was called for (unlikely)

  • A damaged or failed oxygen / o2 sensor

  • Downstream oxygen sensor (Ho2S) wiring damaged or connected improperly

  • The engine coolant temperature sensor is not working properly

  • Damaged or leaking exhaust manifold / catalytic converter / muffler / exhaust pipe

  • Failed or under performing catalytic converter (likely)

  • The oxygen sensors in front and behind the converter are reporting too similar of readings

  • Leaking fuel injector or high fuel pressure

  • Cylinder misfire oil contamination

Resource: ODB-Codes


cat 2