[Nick07]

Ok so my wonderful (yes, sarcasm) Monte is throwin the code for rear o2 sensor low voltage. I checked the wiring and it all looked good but that's not to say it IS good, is there any other things that would cause this code to be thrown? Such as maybe a bad connector or dirty connector? Or is this a rare case where the o2 sensor isn't completely junk yet? I cleaned the connector ends pretty good and like I said the wiring LOOKS good, and I know usually the o2 sensors are either good or bad so I don't think it's the sensor but you never know I guess. Anyway, insight would be great. I don't want to pick up a new sensor if it's not the problem

[me6894]

What's the code? It's almost always the sensor. Any other codes with it?

[Nick07]

me6894, on 16 January 2010 - 12:16 PM, said:

What's the code? It's almost always the sensor. Any other codes with it?

P0137 would be the code, also the only code. I figured it it was a bad o2 sensor it would throw the P0136 code for o2 sensor malfunction

[me6894]

137 is for the sensor after the cat. Do you by chance have an aftermarket converter?

Action
Value(s)
Yes
No

1
Was the Powertrain on Board Diagnostic System Check performed?
--
Go to Step 2
Go to Powertrain On Board Diagnostic (OBD) System Check

2
•Engine at operating temperature.
•Operate vehicle within parameters specified under Conditions for Setting the DTC criteria included in Diagnostic Support.
•Monitor HO2S 2 voltage displayed on the scan tool engine data list.
Does the HO2S 2 voltage remain below the specified value?
100 mV
Go to Step 4
Go to Step 3

3
•Turn the ignition on, and leave the engine off.
•Review and record scan tool Fail Records data and note parameters.
•Operate vehicle within Fail Records conditions as noted.
•Using a scan tool, monitor Specific DTC info for DTC P0137 until the DTC P0137 test runs.
•Note test result.
Does scan tool indicate DTC P0137 failed this ignition?
--
Go to Step 4
Go to Diagnostic Aids

4
Disconnect HO2S 2 and jumper the HO2S 2 low circuit (PCM side) to ground.

Does scan tool indicate HO2S 2 voltage near the specified value?
450 mV
Go to Diagnostic Aids
Go to Step 5

5
•Turn off the ignition.
•Disconnect the PCM.
•Check the HO2S 2 signal circuit for a short to ground or a short to the sensor ground circuit.
Is the HO2S 2 signal circuit shorted?
--
Go to Step 6
Go to Step 7

6
Repair the HO2S 2 signal circuit. Refer to Wiring Repairs .

Is the action complete?
--
Go to Step 8
--

7
Important: : Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming .

Replace the PCM.

Is the action complete?
--
Go to Step 8
--

8
•Turn the ignition on, and leave the engine off.
•Review and record scan tool Fail Records data.
•Clear the DTCs.
•Operate vehicle within Fail Records conditions as noted.
•Using a scan tool, monitor Specific DTC info for DTC P0137 until the DTC P0137 test runs.
Does scan tool indicate DTC P0137 failed this ignition?
--
Go to Step 2
System OK



Hope the flow chart helps

[Nick07]

Well.... I don't have an aftermarket cat and I only have a simple code reader I picked up at Sturdevants for like $65 and some of that was over my head. I get the jist of what your sayin but can't do most of that with just a code reader. Is there other ways to check that voltage? I'm very limited on tools cuz I'm at my g/f's parents' house for a couple days. Also I did get a DHP pcm that is for a 96 but I don't think that's the problem cuz the code just came up recently and I've had that pcm in for a couple months already. Plus if the o2 sensor is the reason for my car running the way it is, it's been running like that since I bought it back in March. Should I just suck it up and buy a new o2 sensor or what

[Dave96Z34]

You get that code if your rear o2 isnt hooked up. You can check the voltage at the harness on top of the pass front strut tower conector voltage back to brown. Then check that at the sensor.

[Nick07]

Dave96Z34, on 16 January 2010 - 08:52 PM, said:

You get that code if your rear o2 isnt hooked up. You can check the voltage at the harness on top of the pass front strut tower conector voltage back to brown. Then check that at the sensor.

Would I also get that code then if the sensor itself is bad?

[me6894]

You can check voltage with a voltmeter you don't need a scanner. It could be a bad sensor.

[Nick07]

me6894, on 16 January 2010 - 10:39 PM, said:

You can check voltage with a voltmeter you don't need a scanner. It could be a bad sensor.

That's the plan for the weekend is to find a voltmeter, g/f's dad doesn't have one and my seemed to have mysteriously disappeared. Which wires should I check and for what voltage? I could probably look it up but I figured I just ask so the info is here for someone else if they need it

[Dave96Z34]

black to brown 12v

This post has been edited by Dave96Z34: 16 January 2010 - 11:31 PM

[Nick07]

Nice, thanks

[Nick07]

Well I couldn't track down a voltmeter or multimeter and wasn't gonna pay $50 for one where I live so I just went to a shop in town and he was nice enough to use his fancy shmancy scanner on my car and it's the o2 sensor itself, voltage is fine. It's gonna be a biotch gettin that thing out, I'm pretty sure it's the original one

[RedZMonte]

you said you have a DHP computer? if someone is local to you with DHP tuner then have it disabled. I disabled mine with my OBDII swap.. no cat or 2nd O2 and no codes.

Just a thought

S

[Nick07]

RedZMonte, on 19 January 2010 - 09:09 PM, said:

you said you have a DHP computer? if someone is local to you with DHP tuner then have it disabled. I disabled mine with my OBDII swap.. no cat or 2nd O2 and no codes.

Just a thought

S

Well I already got the new o2 sensor on order (if the other guy doesn't get it first) from a guy on w-body so it's already taken care of. I'm pretty sure no one around here has a DHP tuner cuz I'm like the only person that's interested in modding any w-body cars enough to get a tuner. I'm like 98% sure that the new o2 sensor will get rid of the code and take care of my car running like a frickin ri-tard

[Nick07]

I guess I'll just add this here.... I couldn't get the one I found but I found some other o2 sensors. The one in question is a universal fit, part number USOS-4000. It's popped up in a couple sites when I enter my make, model, etc. and I need to save money right now cuz I got bills due soon. It doesn't have a plug but it has 4 wires that you just have to connect with butt connectors or whatever, is this gonna work on my car or not? Car is a 96 Z

[Dave96Z34]

yes if you cannibalize the old sensors plug if its not the same.

[Nick07]

Dave96Z34, on 21 January 2010 - 11:26 PM, said:

yes if you cannibalize the old sensors plug if its not the same.

Yeah that's true, I was thinkin hard wire it in cuz that's what they implied by including butt connectors with the sensor. I found a cheaper one by Standard Brand that I think is better than that other universal one I had mensioned before

[Nick07]

So.... I just put in my new o2 sensor and it seems like it helped, but I can tell that there is somethin else not quite right. I cleared the code like a week and a half ago and it didn't come back but the car still ran crappy like before. Weird but whatever, so how am I gonna be able to tell if the car still has issues without any codes? Before I bought the new sensor I had a shop do a full scan and he came up with nothing (other than the "low voltage" code), although the o2 sensor voltage was fine. So I replaced the sensor, no codes yet, and the car still doesn't seem quite right, but better than before. For now anyway

[Nick07]

Another update, I still need some help. Like I said I replaced the rear o2 sensor and today the P0137 code came back and the car still runs just like it did before. I still can't figure out what the hell is wrong with this car, the voltage is fine even though it's throwin the "low voltage" code. Anybody have any ideas at all?

[Dave96Z34]

Its prob geting weak signal from the sensor prob corosion in the harness. The rear o2sensor plays no role in how the engine runs its just there to tell you if your cat has gone bad. If its not running that good thats the not the reason. Could be many things.

This post has been edited by Dave96Z34: 07 February 2010 - 01:09 PM

[Nick07]

Well I ordered a new cat cuz it probbaly needs to be replaced anyway with 195,*** miles on the car and after I replaced the o2 sensor with no success I started thinkin about how the car was acting and a clogged cat kinda made sense. It was either buy a new cat or buy the front o2 sensor, the cat made more sense so I went with that. It's been a guessing game from the the day I bought the car and everything I've fixed or replaced hasn't fixed the problem so more guesses don't really hurt. Eventually something will fix it, plus most of the things I've replaced needed to be replaced anyway. We'll see what happens when I get the cat on the car

[Dave96Z34]

Thats a good start.