well, when I went back to stock and got an whole exhaust system from a different Cavi, my check engine light showed up after one mile. I unhook the battery and reset the PCM, it goes away for another mile or so, then came back up. Tried resetting the PCM again and again, and the light would never go off. I take it to Autozone for check up and it was the o2 after the cat. Well I check on the price of a o2 sensor but had problem replacing it myself. It look like the o2 is welded to the exhaust pipe instead of the screwed in on like the one on the manifold. Anyone replaced theirs yet?

i have replaced mine, it was screwed in but rusted pretty good.. spray it down really good with some PB blaster and let it sit and still you might have to apply some heat to it.
the threads wound up coming out with mine so be carefull it might be easier for you to just leave that one and have another bung welded on and put another one right next to it, just my $.02 ooh and if you havent found it yet the sensor goes for about $93 on the web.

also the more i think about it its odd that the light comes on that soon.. usually takes a while for that sensor to throw a code, make sure you check the wires good maybe there shorted to each other somewhere or maybe its a bad connection at the plug under the hood.. do you remember the code it was throwing off hand?

Ussually takes a complete heat cycle and that code would throw on the 2nd heat cycle. I'd also start by looking at the connection under hood for that sensor, and the wiring because it shouldn't throw that code that quickly.


15.3 @ 89.97mph, 14's on the way?

Could be GM playing their old tricks again. I needed some wiring info, and the shop manual was NOTHING like mine. Not true for every case, but just about every car seems to have its own individual wiring scheme. As for removal, did anyone think of removing the sensor while it's hot, aka at operating temperature? I got my primary O2 sensor out when the system was hot, and it was no difficult than as though it'd just been installed at the factory not 2 hours ago. Sensors real age? About 115,000 miles.

like i said when i emailed you i have a brand new ac delco one in package ill send to u for 40.00 it is the 2nd 4 wire/heated sensor