I have a 2002 SR5 that is throwing a P0420 code and check engine light. I have had the sensors replaced. Still throwing the code. Before I pop for a new catalytic converter, I am willing to try a $25 bottle of cataclean.

The problem is I have just completed the very very laborious drive cycle on this car for the third time in two months. I know I am going to have to do it at least one more time after the catalytic converter is replaced. I would really rather not do it again just to see if the cataclean works, therefore, I am reluctant to manually clear the codes again.

My question is, if I follow the Cataclean instructions, will the codes and the check engine light clear on their own? If they won’t, and it requires a manual clearing, I’m not going to bother and I’m just going to have the catalytic converter replaced.

This is for California emissions, smog check.

Maybe, maybe not. I have a 0% success rate on 2 of 4 cars. A guy I know has a success rate of 75% on 3 of 4.

Good luck

My 420 code cleared with it only to come back later when my antifreeze burning was more apparent.


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I'm not sure if a P0420 code does it, but some types of codes will temporarily set a CEL, or not set a CEL at all, but the code will still be stored.

Stored codes won't clear themselves.