O2 Sensor [Archive] - GrandAmGT.com Forum


View Full Version : O2 Sensor

08-04-2006, 07:33 AM
this is really starting to grind my gears. my check engine light has been on for a while now. about a year ago when i put on my TOG headers, is about the time the light came on. scanner said O2 sensor before the cat. so needless to say i replaced it. the light came on again about a week later. same code. at this point i thought maybe the wire extension had touched the headers and maybe burned through. there was a place on it that the black plastic tube around the 4 wires melted, but none of the wires were exposed. i figured who cares, i'll just replace it. i did so, and made sure it was not anywhere near the headers. the light did not go off. so i finally decided to spend $90 and get a new O2. took it right over to autozone, they reset the code, and about 5 miles later the light was back on. took it back to AZ they told me it was the o2 before the cat. so now i dont know what to do. it doesnt make sense. wouldnt my gas millage be bad if my o2 was bad? last weekend going 70 mph, i was getting 35 mpg. i'm stumped. no clue. the light is not only anoying being on all the time, but if anther one of the 120 sensors f*ck up, then i wont know about it. anyone any suggestions?

08-04-2006, 08:26 AM

Hahaha we are so on the same boat.

08-04-2006, 08:34 AM
well that was more informative then the last link. ok, let me also say that my car runs fine. the only thing it has been doing, and only like once a week, is hesitate at about 1500 rpms. but if i get into the gas it stops. and its only on a cold engine. i dont know if that related. so a pcm short? interesting. ok so 2 more questions. would a pcm programmer fix this, and if not, i am going to have to get a new pcm arnt i?

08-04-2006, 08:45 AM
I really dont think its PCM related, so hard to believe it would be.
I have the same exact problems you do though.

08-04-2006, 08:51 AM
maybe that would explain my high QM times. my light was on when i ran. do you think it could be?

08-04-2006, 08:54 AM
I ran when my light was on but at that time there where no symptoms that i have now, i still ran 4 14.9's.

08-04-2006, 08:59 AM
hmmmm, well that sucks, for me. i just dont have any clue how to turn the d*mn light off. so far i have waisted about $150 and 3-4 hours. i am about ready to take it to my mechanic and tell him i dont care what he has to do, turn the light off.

08-04-2006, 09:22 AM
Im about at that point also. Just dont know what else to do. At least i know a good mechanic who loves my car. Im gonna grant him his wish and let him tinker with it. I really dont want to do that though.

08-04-2006, 09:27 AM
i know what you mean. i think were just out of options. also i dont want my mechanic to buy a new o2 for it, cause my o2 should be fine. its less then 2 weeks old. and i hate being without my car.

08-04-2006, 09:35 AM
Yup mine is only 2 weeks old and has MAYBE 100 miles on it.....more like 60 miles lol.
Im taking it to AZ after work to get the codes read again.

08-04-2006, 09:50 AM
lets keep each other updated on this.

08-04-2006, 10:45 AM
No problem man.
I just went to lunch and it didnt act up at all but i bet when i go home its gonna act up on me.

08-04-2006, 11:17 AM
lol, looks like we have the same luck too.

08-04-2006, 11:24 AM
Im starting to think its the color red lol

08-04-2006, 12:39 PM
hey, if this is the only problem i have with mine, i'l be happy

08-04-2006, 12:56 PM
I feel ya on that for sure.

08-04-2006, 01:48 PM
What is the actual trouble code.

08-04-2006, 05:55 PM
Im goin to AZ tomorrow, didnt have time today. I will post the code when i get it.

08-07-2006, 01:36 PM
anything new Coupe?

08-07-2006, 04:08 PM
Ive driven it 40 miles and it seems totaly fine. Light is still on but no ill affects of any kind. I didnt get the code read yet.

08-07-2006, 07:48 PM
In case anyone didn't know, the reason it takes 50 miles before the code comes back on is because when you delete the check engine codes, you reset all the readiness monitors...misfire, catalyst, egr, evap, 02..all that fun stuff, so it takes driving, usually 100 miles to get all the codes to ready status... and so when the 02 readiness code is about to set, whatever problem there is, it is sending back to the pcm that there is a problem with the 02 sensor.

08-07-2006, 08:13 PM
thats exactly like mine is. i dont see how i can be getting 35mph with 4 adults at 70 mph, when my o2 sensor is messed up.

and it takes about 4 miles to turn back on, not 50.

08-07-2006, 10:05 PM
man i would kill to have 35 mpg, im lucky if i get 24 anymore. anyhow.. this probably isnt your problem but.. i had a hesitate problem with my the other week, and when it was idling the rpms would go up and down.. some how my battery cable was lose. *shrug* worth a shot to check to see if it will resolve that problem atleast.

08-08-2006, 09:02 AM
thats exactly like mine is. i dont see how i can be getting 35mph with 4 adults at 70 mph, when my o2 sensor is messed up.

and it takes about 4 miles to turn back on, not 50.

Yup takes about 4 miles.

10-10-2006, 01:22 PM
i was thinking about this the other day, and i think i might have figured this out. but, i could be wrong, so thats why i'm running it by you guys first. i bought my TOG headers, and my borla off e-bay. they were both used. it was from a dealership, they took it off a trade in. any ways i remember reading something about the cat being clogged with the coating they put on the headers. mind you that this happend right after i put both the headers and exhaust on. my wonder is, if its clogged up, could exhaust be coming back up to the first o2 sensor, causing it to throw a SES light? that would make a lot of sense considering i am on the second o2 sensor, and have replaced the harnes. it might also explain my poor QM times, for what i have done to the car. i dont know, it just kinda dawned on me, and seemed to make sense, but again i'm not exactly sure. i could be wrong. so any more help would be great. thanks again guys :cheers:

10-10-2006, 06:54 PM
Thats definately not gonna be my problem.
Im still runin 14.9's.
If my cat was clogged there is no way i can still run 14.9's consistently.

10-11-2006, 08:42 AM
beats me Coupe, i'm running out of things that can be wrong. does that atleast make sense?

10-11-2006, 09:31 AM
It makes sense to me.
Hell im out of ideas.

10-11-2006, 12:24 PM
i'm thinking about just getting a high flow cat, and just seeing what happens. the really odd thing, is that the 2 of us both have differnt brands of both headers and exhaust, and we have the same d*mn problem.

10-11-2006, 04:06 PM
You could try that, worse case it wasnt the problem but at least you will know you have a full free flowing exhuast from headers back.

10-11-2006, 08:42 PM
i was thinking that i have the stock one just laying around. maybe i'll just bolt it up this weekend and see what happens

03-08-2007, 12:15 PM
ok update. had to have my car go in to my mechanic to do a wheel bearing. any ways i told him about this little problem. he said that it could be a couple of things that i had not thought about. first he asked where the place of the o2 sensor was on the headers, as compaired to stock. i told him i didnt know, its been a while. so he said that if the o2 sensor gets far enough away from the engine, it wont get enough heat, and throw a code. as i started thinking, i think i had to get a o2 extension harness when i put the headers in. so thats a big possibillity.

other thing is said is that after everything i have done to the engine to get more air into it, i may be running lean. now i dont know where, but i have read on here that stock injectors do fine when modded, and that there is pretty much no reason to change them unless your boosted.

at this point i dont know what it is. but i know what i'm going to do is get my hands on a air/fuel gauge. and if thats fine then maybe i'll modify and move my o2 closer to the engine. its worth a freakin shot.

03-08-2007, 01:04 PM
I have a hard time believing that.
For me anyways.
How can it take 2+ years to finaly throw a code?
Thats how long i had them in for before i threw that code.

03-08-2007, 01:45 PM
huh. i have no idea. all i know is mine came on after my header install. not to long after, but after non the less. maybe when i'm done with the a/f guage, i'll ship it to you. it cant hurt, right?

03-08-2007, 03:11 PM
GA's use 4 wire heated O2 sensors. You can pretty much put them anywhere and they will work. Even in your tailpipe, although the signal would be really off due to reading outside air, but not from it being too cold.

As for injectors, you don't have enough mods yet to need larger injectors. I know this from monitoring the injector pulse on my own car which has stock injectors. Stock injectors don't show there limitations unless you go boost or get a cam.

I also would be very careful on which Air/fuel gauge you get. If it's one designed to read just the O2 signal (Autometer gauges are like this) then you really won't know if the car is lean or rich. The lights are not calibrated for actual air/fuel measurements. Instead they are a generous guess and basically just provide a light show inside the car. It you really want to know if your rich or lean you need to install a wide band O2.

Did you try switching out the catalytic converter? What is the DTC?

03-08-2007, 04:06 PM
ok so maybe there are 2 patterns here, you are both reading the codes at auto zone, and maybe they are telling you the wrong sensor, also you are not getting the code. and C...did both of you get your sensor from AZ...thats something u have in common, or is it the same brand. honestly i dont buy any O2 sensor from an auto parts store, i get mine from GM...and they cost me less than $120 and they are exactly stock. this is why spruce keeps asking what is the code, alot of it can have to do with the wiring...

03-08-2007, 04:24 PM
I have to waite till spring to get my code read again, i dont remember what it was.

I have a Denso O2 sensor. Highly recomended by the GP guys, we use the same sensor BTW.

03-08-2007, 04:33 PM
well i know we used the denso, but is it just a denso or an AC Delco Denso?

03-08-2007, 04:51 PM
shortly after my TOGs were installed my car threw the upstream o2 code (P1133). i replaced it with a bosch o2 from auto zone and have had no problems since. it was only $80 IIRC.

03-08-2007, 04:52 PM
yah when i got my ss headers i figured cheap insurance would be to replace the sensor, looks like i made a good choice

03-08-2007, 08:45 PM
my sensor is a ac delco denso. is that bad?

03-08-2007, 08:46 PM
no, thats what they normally are, but i would just double check the code you are getting, then check the wiring harness and maybe put some dielectric grease in the conn.

there may be secondary voltage leaking from the spark plug wires, make sure they arent laying on the O2 wires

03-09-2007, 08:16 AM
as far as the code, i've checked it atleast 5 times. same cold. o2 low volt. i think its code # 183. or something real close to that.

i made my own wiring harness to replace the other one thinking that could be the problem. nope.

i'll check the wires tonight. but i doubt its the case, cause i've replaced wires sinse the light has been on.

03-09-2007, 10:07 AM
then maybe its time to look at a scan tool to make sure it is getting the low voltage, and also hook up a meter to check and make sure it is getting the normal voltage supply and that there isnt excessive resistance in the wiring, that would cause low voltage also...just a few thoughts

03-09-2007, 10:20 AM
also the DTC for sensor 1 bank 1(which is the upstream) is P0131 for sensor low voltage. ther isnt a P018x in the DTC list AFAIK...so on that note lets look at the cause of the code, which is

The DTC will set if either of the following conditions are present for up to 50 seconds :
The HO2S 1 signal voltage remains below 175 mV during Closed Loop operation.
The HO2S 1 signal voltage remains below 600 mV during power enrichment (PE) mode.

so there are 2 reasons.

your only options for fixing it are replace the sensor, check wiring for a short to ground, check PCM harness to make sure it is ok...or replace PCM. also about the wiring, if you just make a harness, it might be affecting the sensor, having maybe too much resist in the wiring. also check for any damaged or questionable wiring, the wrong fuel pressure, the evap canister purging at the wrong time or all the time, an exhaust leak or any other obstruction in the exhaust to keep the O2 from getting a good clean air reading, or a contaminated one. those are the only options. and those are directly from the manufacturer.

03-09-2007, 02:00 PM
as far as the code, i've checked it atleast 5 times. same cold. o2 low volt. i think its code # 183. or something real close to that.

i made my own wiring harness to replace the other one thinking that could be the problem. nope.

i'll check the wires tonight. but i doubt its the case, cause i've replaced wires sinse the light has been on.

I think you mean this code:

P0138 - Heated Oxygen Sensor (HO2S) Circuit High Voltage Bank 1 Sensor 2

not this:

P0183 - Fuel Temperature Sensor Circuit High Voltage.

Now the Bank 1 Sensor 2 O2 is the one located after the catalytic converter. Have you been working on it or the one located in your headers?

03-09-2007, 03:47 PM
its the one before the cat.

03-09-2007, 08:20 PM
have u ever tried replacing the one behind the cat? just a thought, and spruce has the same idea i do

03-09-2007, 09:31 PM
no, but its easy to do. is it the same size as the one in front of the cat?

03-09-2007, 09:55 PM
It's the same sensor.

03-09-2007, 10:05 PM
sweet, i'll give it a try.

yeah, i'm not 100% what exact code it is. all it says is something like o2 band 1 low volt. so thats all i know.

03-10-2007, 12:10 AM
whoa wait a minute, when i got my upstream it was alot different than the one after the cat...not sure y though, but it didnt have the flowerlooking shield on it and it was a denso ac delco, the other i think is a bosch downstream, they are both genuine GM no aftermarket, also the harnesses are different lengths, so have fun with that

and one of the codes i gave u was for the upstream O2, the code for the rear is P0137...thats the rear sensor low voltage, so those are the only 2 it could be if it was low voltage

07-08-2007, 11:05 AM
Dude, check fuse #47, under hood fuse box.

Mine was blown all this time and didnt even know it.

The Beyond
07-08-2007, 01:24 PM
will this work with my 96' GAGT 3.1?

http://cgi.ebay.com/ebaymotors/NTK-NGK-O2-OXYGEN-SENSOR-PONTIAC-GRAND-AM-PRIX-SPORT_W0QQcmdZViewItemQQcategoryZ33557QQihZ020QQit emZ300083433297QQrdZ1QQsspagenameZWD1V

ive been getting really bad mpg and i was thinking i would start here...

NTK a junk brand?

07-08-2007, 01:52 PM
Are you throwing a code?

The Beyond
07-08-2007, 02:28 PM
nope, i just bought the car a couple months ago, 170,000 on the body and 60,000 on the engine, The plugs/wires are brand new and about a month ago i put on a CAI with a 3 or 4" K&N. (mpg sucked before cai) i just took a quick look at the o2 by the cat.. looks ancient, prob has never been changed... i guess im not sure if this will help my crap mpg but i guess i need a starting point...

Ive heard that a bad o2 might not set of a ses...

Also, any idea where this other o2 is?


The Beyond
07-08-2007, 04:32 PM
I found the other o2.. it looks pretty new... i dont know

07-08-2007, 04:34 PM
yes an o2 sensor can be bad (not working correctly) but not throw a code.... this would most likely result in decreased MPG and performance

The Beyond
07-08-2007, 04:50 PM
how important is that lower o2 sensor (next to the cat)?... that one looks pretty old..

07-08-2007, 06:38 PM
IMO, not that important if at all.

The Beyond
07-09-2007, 12:09 AM
i filled up the tank (first time...) and got some STP fuel injector cleaner, im gonna try and calculate and see how bad my mpg really is..