I've attempted to get my check engine light fixed a couple times and at each repair facility they've scanned the code and told me it was a bad oxygen sensor. I had the oxygen sensor replaced at both shops and neither time did the check engine light stay off; it immediatly came back on. Both businesses seemed dumbfounded as to why they couldn't fix my car's problem.
Doing a little more research, I found the following tidbit:
The problem is the an OBD2 scanner will read the code that the PCM is "throwing", meaning that there is a problem in the circuit that contains the O2 sensor. This can be caused by several different parts of that system, EGR valve, spark plug, coils, MAF sensor (Mass Air Flow), etc. There is no code that tells exactly which part needs to be replaced.
So if that's the case, then how exactly do repair shops go about fixing a check engine light for an O2 sensor? You'd think they'd be up to the task since that's their job and yet somehow I've paid for 2 repair jobs that didn't fix the problem and am reluctant to attempt it a third time since its likely to fail.