PO420 catalytic convertor diagnosis

[Dave S.]

For a CAMRY 2000, 142000 miles, with a PO420 check engine code, my mechanic is looking for a way to determine whether the front or rear catalytic converter is causing the problem. Visual inspection does nor show a difference. Any suggestions? I understand that there is a service bulletin. Where can I find it on the web?

[Vicoor]

Hello Dave.
I haven't seen a TSB on P0420 for that model. The new systems are very sensitive and will set these codes quickly. some of the conventional methods of testing don't necessarily yeild good enough data for results. I'd say that if you've cleared that code and it comes back then I would inspect very closely for small exhaust leaks upstream of the cats. sometimes these can be fouund when the vehicle is started from cold as you will get some condensation from the exhaust wetting or dampening the area around the leak. If there are no leaks then I would target the main catalyst first. Unfortunately this will likely be your course of action.

Hope this helps

As an introduction, I would like to say hello to everyone. I am a veteran Toyota technician with an extensive background in diagnosis. I've worked for 2 different Toyota dealers and several independent shops, one of which I am currently employed at. I won The Regional Technicians Skills Contest while I was working for Ourisman Fairfax Toyota. So if I reply to someone about Toytoa diagnosis I would say to give my suggestions a strong consideration, even if it is not what you want to hear.

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