Stinking O2!!!

I have an 03 GT w/125k miles. Just replaced the catalytic converter with a magnaflow converter about 10k miles ago. Car has run great and still does, but it recently threw an oxygen sensor code for both sensors. I replaced both sensors, and cleared the code (with a scanner). A few hours later, it came back. There is a third code showing and I can't remember what it was at the moment, but it was something about a switching mechanism. Any ideas? I'm going to replace the TPS sensor this weekend... I heard a tip from a local that it could be related, but I'm not sure I believe him.

Any ideas? All three are brand new... not sure what to do at this point. Codes clear and keeps the light off for a day or so, but then they come back.

Thanks guys.

As long as you have that hi-flow cat installed, you will most likely never get rid of the Catalyst insufficient code. This is due to tehe high flow cat trading efficiency for flow rate. An aftermarket rear o2 simulator or reprogramming of the PCM to eliminate the catalyst monitoring would be your best option. AS far as the "Switching" code, this is indicating that your o2 isn't heating up properly, which could indicate a bad new sensor or the wiring associated with it.

Will I still pass emissions testing with the O2 simulator? I realize it will get rid of the light, but emissions test is what i'm concerned with. I have to go test soon and I'm trying to either A) Sell the car in the next few days or B) Get it emissions ready.

It depends on the state and how they do emissions testing. I've had no problems passing in Texas using a 02 simulator in my GTP or Olds Alero. As long as there is no SES/CEL light on and emissions readiness status (IM) or flags are good it should be good.

Getting a post CAT DTC like P0420 is common when using a Magnaflow hi-flow converter or even headers.

you dont want to reprogram the pcm. The 02 simulator will run you about 40 bucks on any of the grand prix performance sites. with the simulator, you will only get the light about every 10-12,000 miles.

www.zzperformance.com (http://www.zzperformance.com)
www.3800performance.com (http://www.3800performance.com)
www.grandprix.net (http://www.grandprix.net)