Bad O2 Sensor NEED HELP!!!

**TransAm11973** · 11-22-2007, 11:30 AM

My SES light came on for my Bank 1 Sensor 1 O2 . Had Pontiac check the code. They said the sensor was bad. I replaced the B1 S1 o2 sensor with a relatively new one that I had. Then I had the code cleared. It was good for a day and then came back on this morning. So now I dont think its the sensor, and pontiac is full if SH-T. Is it the wiring? MAF? I have SLP headers ,MAF etc etc. I am not sure where to go next. I know this is a commom problem so hopefully someone can help. Really pissing me off. THANKS!!!! Also is this SES light gonna throw of my AF ratios now???

**89LX** · 11-22-2007, 11:43 AM

Switch sensor from the other side if you want as they are the same. If you get a light on the opposite side then you will know if it is a bad sensor you moved over. Last time it happen to me I thought it was a bad sensor but turned out being a small exhaust leak where the header extension pipe fits prior to the tail pipe (y-pipe).

**TransAm11973** · 11-22-2007, 12:59 PM

i already switched the sensor once. honestly i dont think its that. there was a small plug that fell off my cat, for a diff type of sensor which that car doenst use. I plugged it but maybe not good enough. it is in the middle of the cat after the first o2 sensor. the cap that fell off is the size of a valve stem cap, could that be whats making the light come on? Not a wiring problem? thanks

**0rion** · 11-22-2007, 01:25 PM

what code was it? There are a couple for the O2's. Might not be a bad sensor at all but one showing lean or something. Need the code to give you much help other than guesses.

**89LX** · 11-22-2007, 02:03 PM

I wouldn't think it is wiring or you would more than likely have it all the time unless a wire is chafing.

**TransAm11973** · 11-22-2007, 02:14 PM

the guy at the pontiac dealer said it wasnt high enough on the milliamps i believe, running around 400 -500, said he wanted to see it around 1100 or so.

**TransAm11973** · 11-22-2007, 05:59 PM

anyone have any other ideas? i a still stuck

**Bigjohn366** · 11-23-2007, 12:11 AM

alot of the time i just add a little seafoam dont even need to mess with the sensors

**TransAm11973** · 11-23-2007, 06:35 AM

does anyone know if i just delete this o2 code, will it be bad for my engine. its bank 1 sensor 1 so its the important one. is this going to eventually make my af ratios go all screwy? i checked the wires they are good, i checked the o2 sensor it is good as well. why would it show that the o2 is running low voltage? if i clear the ses light, eventually like a few days later it just comes back on. I found the hole in the cat. and sealed it so I will reset it today and go from there. right now the car is running great, no problems except for the damn light. HELP any one run into this problem as well?

**JL8Jeff** · 11-25-2007, 08:14 AM

You need to find the real problem. If the computer isn't getting a good reading from the front O2's it can't make adjustments and will go into SD or limp home mode. It might be a grounding issue of a harness extension problem. Clean the threads on the sensor and header real good to make it's not just a grounding problem. New headers will burn stuff off that can ruin the sensor so you still might want to try swapping side to side. But it sounds like a wiring issue on that side. Make sure the wires did not contact the header and melt anywhere.

**TransAm11973** · 11-25-2007, 09:19 AM

ok thanks, i did that and the wires look good. i will have to check the ground. I took the sensor off again cleaned it and spread the fins. Then I turned my MAF 1/4 of a turn and cleared the code. Since then believe it or not its been fine. very strange. any ideas on that?

**ls1speedster** · 11-25-2007, 01:45 PM

Seen many people on here have low voltage to the oxygen sensors..
im throwing codes both banks low voltage
i have over ten codes getting throwed...
all four oxygen

was told to check all the wires..which i am ganna do..but have heard then that may not even be the problem if all look secure..

is there any other problem that this could be from...dont want to replace them if it is not the problem...
i have pulled them out cleaned and then put back in..all the pig tail wires off the sensors have good connections..where do ground wires run.??

this is a very common problem..

**TransAm11973** · 11-25-2007, 06:30 PM

speedster....do you have a bunch of mods on your ride??? well all my wires checked out too, the ground should run up and screw in somewhere on the top side area of the driver side wheel well, near the fuse box. my shit was throwing metering codes and o2 codes, i di da few small things to try to fix it, opend fins, turned MAF, which doesnt make much sense but it worked, i am still confused but my SES lights are out. i still have yet to get a really def. answer on this question, seems to be quite common like you siad, lots of ideas but no one knows for sure, all i can say is go through the typical list, swap o2 sensors side 2 side, check plugs, fins, wires, ground, fuses ecm.

**eatsrice** · 11-25-2007, 07:09 PM

Hey I also had the ses light come on and I checked it and it said b1 s1 o2 sensor was bad! It happened the day after I had my exhaust cutout put on! which is also the day I bent the flange on the cutout so I am un able to close it to see if it makes a difference! maybe your headers are the problem!

**ls1speedster** · 11-26-2007, 01:45 PM

no mods here...
bone stock
K&n filter
and ported T/B but codes was throwed on before port

thanks for the info, i ha ve pulled all cleaned and checked....will swap and see...will also check wires...will try the spin of the maf sensor...