Car tossed this same code almost a year ago and I was about to try the ZZP O2 Bung Extender but the light turned off and never came back on, well till now anyways. Car is running fine and when I fist pound the cat I don't get a rattle sound. No rotten egg smell either. Way I look at it I got 3 options. The bung, toss a o2 sensor at it, or get a ZZP PCM to shut off the rear o2 sensor. Think its worth it to try a sensor? Normally if its a sensor it toss the heater circuit code as well. Does the bung hurt MPG or drivability at all? ZZP says right on the site "We do not recommend running without the rear o2 sensor because it could run the rear o2 test and reduce your gas mileage" that worries me about going with the tune option.
So whats should I do? I guess buying a new cat is an option but a GM cat is like 700 bucks, Amazon shows an ACDelco AFS141 for like 33 bucks. I'm not sure if this is upstream or downstream. I think it's the down stream....
