Hello, it has been about two months since my check engine light popped up and had a code showing P0420 OBD-II, seeing as my tags were in need of replacing I took my car to a catalytic converter shop to get it fixed. I took my car, they took a look at the sticker under my hood and replaced bought a part. They replaced a catalytic converter that under the part name 448005. A few weeks later my light came back on and it was for the same reason, they then told me that my car has 2 catalytic converters and that this new catalytic converter can run up to $800-$1200 because it would be a dealer item only. I have been checking online non-stop ever since my mechanic blew me off and told me to find and buy the part and they would install it and the only part that shows up is 448004 for a much cheaper pricing than originally estimated. Am I searching for the wrong part? Every mechanic I go to tells me they can't help me because it is a dealer item only and they can't get the part. One shop told me they can do it for $220 which sounds reasonable, but I am not sure if they would be looking at the first catalytic that was replaced (cost $180). I just want to make sure I end up purchasing the correct part as it seems catalytic converters for Volvos are suppose to be much more expensive. (In CA, need CARB catalytic).

 

there are going to be different exhaust part numbers for the California compliant cars vs the rest of the US. Best to use a dealer parts web site like OEM Volvo Parts | Volvo Wholesale Parts Direct to get a diagram and proper factory numbers. To note, what the P0420 is telling you is there's too much of a delta between the front and rear O2 sensor's reading. That could be caused by the cat not getting fully up to temperature, one of the sensors is off or even the mixture is off (ie exhaust or vacuum leaks may trigger a 0420 but most commonly it will be part of a list of codes). Its not uncommon for the gen 1s to develop exhaust leaks by the flex pipe. Is the car burning any oil? if so, that could lead to premature cat failure.

 

Before you replace the cat, make sure it is bad.
The Misleading Nature of the PO42O Code - Eastern Manufacturing

 

AutoNaut and mt6127

Thank you guys for the response, I do appreciate it. I ended up getting my front caty replaced by a muffler shop not too far from my area. It just seems that everyone in the L.A area does not want to work on a Volvo, after seeing these guys struggle with removing the engine and welding everything back into place, I can understand why. I ended up paying about $534 for the part (non dealer, they found it the part), labor, and taxes. I just took the car for a smog check and it passed, so I am happy about that. Regarding the 2 different parts, the only one that actually matters is the piece that is connected to the oxygen sensor and the engine, so I got duped by the first guys, but not by the second guys. The part numbers were all different, but the catys I was searching for were not the ones I needed, glad I found this muffler shop. Once again, thank you guys.