Have a 2001 Volvo s60----not the turbo---and getting this code from the code reader at Autozone----took it to a mechanic who hooked it up to his computer software and he confirmed converter is bad. This car has but 130,000 on it and has no symptoms at all of bad cat--- its running good, no misses, no sluggishness, good blow out the tailpipe, no smoke no rotten egg smell. Any thoughts if there can be anything else causeing this code to pull. I know oxygen sensors can inter-relate a bit with cats BUT I know there are codes that tell you if you have a may have a bad O2 since I've had such in past and put a new upstream in.

If the car was running bad or showed symptoms id bite the bullet and put a cheaper aftermarket universal cat in it. Since its running good with no symptoms tempted to try the cheap downstream O2 hack so many YOutube vids on to fool the puter that the cat is ok.

Any thoughts if this might be a false code triggered by something else wrong ( though the mechs software also said its bad)-------at 130000 mile and running good just have a hard time believing it.

 

A P420 code is the passenger side O2 sensor that's below threshold. P430 is the driver's side. Had the same code. Tried everything to "clean" the system. Ran lots of Sea Foam and even that Cataclean, but nothing helped. Ended up changing out the downstream O2 sensor for $100. Volvo uses Denso O2 sensors. Fixed the problem!

 

Wish I could have faith in that as o2 sensor is a lesser fix but that p420 code does make reference when googled, on here,and autozones printout to catalytic converter, there are other codes for the sensors as I have had them and replaced the upstream twice. I admit possibility DS sensor could fix issue even though it gave me cat code rather than sensor code ( the YouTube hack I mentioned extended height of sensor to fool the internal diagnostics )

Still I would try it-- hate it but will have to take to a shop. It is so I guess rusted into the hole even with penetrating oil cant break it loose. Even worse can not figure out how to release these Volvo electrical connectors

Thanks for your response

 

P0420s can be caused by a failing cat (particularly if the car is consuming oil), bad O2 sensors or can be caused by an intake air leak or by an exhaust leak. I'd check for things like a cracked exhaust manifold, a broken EGR tube (* not sure if your model has one...), leaks by the flex pipe etc and then move forward to look for intake air or boost path leaks.

 

OP, have you replaced the O2 sensors located downstream too?