So my GMC Terrain has a P0420 code. I replaced both oxygen sensors but that is not fixing it. There is an extended warranty on the cat for these vehicles, but of course mine is now just out of that windows. I always go OEM but the cheapest I can find for the OEM cat is around $600 shipped, however I have to pay a $400 core charge, which is not that big of a problem, but still kind of a pain to deal with. I can get an aftermarket walker cat for around $350 shipped. What are your guys opinion on this situation, go OEM or try aftermarket?
Thanks
Thanks