if one or both of my o2 sensors in my cats went bad would I notice anything even though i have a tune that disables them? i know that might sound dumb but i'm just thinking that the tune disables just the error code you get if you have certain hi flow cats or off-road mid pipes. i'd imagine that the computer must need them for something. i could be totally wrong. i ask because lately my car has been running a little wierd and i know how delicate those sensors are and i've taken them out a few times while changing mid pipes and was just wondering if one of them got banged around too much if it would affect anything if it were to go bad...

 

As far as I know, the only purpose of the downstream O2 sensors is to verify that the cats are working correctly. The upstream ones would cause a problem if they were defective.

 

ok and I'm assuming that those would still throw a code if they went even with my tune? thanks