Thread: CAT or O2 Sensor

Originally Posted by Sabrewings

I've seen this a lot. Especially when I worked for a dealer. The O2 sensor goes bad but not to the point that it trips its own code. It shows false readings that makes the PCM think the cat is bad.

If he has a stock cat, it's the O2 sensor.

Do you think that it is actually the 02 going out more of the time than it actually being a bad cat? Especially seeing that these cars usually have a pretty good amount of miles on them? Good info non the less.