I personally think your mechanic is right The way a P0420 is set is that the secondary O2 sensor "wakes-up" under certain engine conditions that the CAT should be able to keep it "asleep".Subterfuge3927 said:<snip>
I have found a decen t mechanic and he feels fairly confident it is not the O2 sensor, but the cat... anyone else have this issue around 93k miles:?:
Difficult call.SamuraiSam said:<snip>
I should just bite the bullet and replace the O2 sensors at the same time just to be on the safe side. Would this be prudent? I use it for my daily commute of about 150 miles round trip.
Thanks Goat. As it turned out the dealer replaced the sensors as well, all under warranty.goat961 said:@ SamuriSam
i replaced my cat at 80,000.... still under waranty thankfully. 2 weeks later my O2 sensor went as well. the O2 sensor was also under waranty even though i was over 80,000 at that point.... not sure why, but for some reason it fell under my 100,000 mile warranty.
might want to check on that.