SFexBOY

i don't remember the actual code #....but it def was the rear O2 sensor.

NoNonsense

i can't say I know how many cycles it actually is...i don't know if there is a method to the madness

JUSTA4 -Matt

I did the same thing but I think mines opposite. I made a piggy pipe with o2 extenders to pull the o2 sensor out... I only got a code maybe twice a year for like 2 years, cleared and no problem. I just recently started to get it regularly and noticed prior to installing my cat delete the hole was pretty black and possibly soot or build up may have accumulated in the the o2 extention piece. I get the code, no activity. I am assuming its too covered and not reading anything now that stuff built up in there. Anyone have any input about this?

Shep 1.8T

It doesn't sound totally out of the ordinary. The sensor might be on it's way out, but like most things they die a very very slow death. It's hard to say if it wasn't also something like you got a bad batch of fuel, and the ECU didn't like the values from the rear 02 etc.

Did you happen to notice any failed emissions readiness codes? They won't pop up as acutal fault codes (at least on the nDBW cars) you actually have to click on the readiness button to see what's up.

SFexBOY

I was using an OBDII, so I'm not sure if I can find those fault codes using this tool. I have a feeling its' probably on its way out, but since it doesn't affect the actual perfomance of the vehicle....I'm actually happier that the light hasn't reappeared yet. I'd like to hold off on replacing this since there are a couple other maintenance items I need to attend to before doing this.