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Discussion Starter · #1 ·
Just curious on what you guys found to be the problem, going through the FSM, the O2 sensor is fairly new, Bosch I do believe ( this isn't my car by the way, just one I am working on) Hooked up my scanner and read the O2 volts on the faulty bank, seemed fine for a second at start up, then almost went to zero when blipping the throttle, but would come back up as the RPM's came down, the O2's when holding throttle steady at 2000 RPM read .8 to .9 but this one is reading .1 or lower. I would think that it could be a possible bad O2 sensor, but unsure, figured I would ask what you guys have run into. Thanks
 

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0151 = Sensor Circuit Low Voltage (bank2 sensor1) which is passenger side-front

IIRC "low" voltage would mean lean and high rich. my scan software is set to read in mv with 100=low up to 800=high

My first step would be replace 02 with a Delco

could swap the fronts from side/side to see if the code migrates to 0131 meaning that O2 is bad.

good luck Mike
 

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i get a p0141 which is low voltage bank one sensor one and shorftly after i get a missfire could the 02 sensor cause a missfire
 

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i get a p0141 which is low voltage bank one sensor one and shorftly after i get a missfire could the 02 sensor cause a missfire
actually 0141 is "heater circuit malfunction" bank 1 sensor 2 which is DS rear. different problem.

you can swap your 2 rear O2's and see if you then get code 0161...which would mean the O2 is bad

beyond that you need to follow diagnostic order in FSM for 0141
 

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Discussion Starter · #5 ·
Yeah you can get a misfire 0300 code with the 0151 not sure on the other one, I think that the sensor went tits up, as stated above it reads really low at idle and any rpm except for at decel, the rear sensor on that side reads normal. The scan tool I bought reads live data which is really cool, I have an extra Delco laying around so I will probably throw that in, need to find my O2 socket though as that sensor is kindof a pain to get to with out one.

Also I did all the diagnostic testing in the FSM came to the part to jumper the low out of the pcm to ground, I got a steady .450 volts, which is what it stated it should be, then it tells you to go to diagnostic aids, and it lists ten things it could be, oh boy what a help :) I will figure it out.
 

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actually 0141 is "heater circuit malfunction" bank 1 sensor 2 which is DS rear. different problem.

you can swap your 2 rear O2's and see if you then get code 0161...which would mean the O2 is bad

beyond that you need to follow diagnostic order in FSM for 0141
maybe it isnt 0141 it gives a low voltage and no signal code then after a couple of hours it just goes away
 

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I had a bad O2 that was causing my car to miss at lower RPM's during closed loop (it sounded like it was pulling out on 6 cylinders), you could also hear/feel it cruising.

It would make all the plastic inside buzz intermittently due to the miss. After the O2 was changed, it's went back to buzzing constantly. (This is due to my droning, you could tell cylinders weren't firing!).

It car also seemed to surge while trying to hold cruising speed.

It took a while for me to pinpoint it as a bad O2, I didn't get any codes, possibly because mine is a 95...

If I ran it long enough like that, It would start screwing up my open-loop tables (idle got terrible and gassier than usual, and at WOT it would miss like crazy).
I could pull the PCM fuse for a min. to reset the fuel trims and it would be ok in open loop for a few days, or until it intergrated the screwed behavior it learned from closed loop to open loop.
 

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Discussion Starter · #8 ·
Yeah that is pretty much exactly when it popped the code first, highway cruising 75, tach about 1800 or so, started to spit and sputter, check engine light flickered and went steady, checked codes and I had P0151 and P0300, low voltage O2 as stated and 0300 is misfire code, cleared them, had the scan tool attached and watched the voltages, up and down in the RPMs in the shop and the code came on after about 5 or 10 minutes of doing this. checked the connectors and all were tight, checked the pins on the O2 itself, checked the harness, as since I just put the T56 in this car figured I would check to make sure it had free play and wasn't pinched anywhere, all is good. The owner of the car popped a code and I am not sure what it was, but he changed the sensor then and it fixed the problem, but it is a Bosch unit, which is pretty much a no no on these cars.
I have an extra set of sensors in my car just plugging the O2 holes until I put a wide band in my car, so I will take one out of there and put it in and see what happens.
 

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Discussion Starter · #9 ·
Ok I am stumped, I put a Delco unit in straight out of the box and it is the same sh$%, O2 sensor reads fine in Open Loop, but as soon as it goes to Closed Loop the voltage dies off to almost 0 and the only time that it comes back is if you run the car at 1500 RPM say and as it is coming down the in RPM range the voltage rises back up.

I checked all the wiring for the sensor to the PCM, ohmed it all out, cross referenced each pin to ground to make sure there was no short and it is all good.

There are no exhaust leaks, if there are I can't hear them and that would tell me that they are significant enough to cause a crazy lean condition, the only thing that I haven't gone through and checked throughly is for any vacuum leaks.

What should a non modded motor, lt-1 that is, read for vacuum at idle. The scanner I bought read this as well, but in all honesty I would think that if it was vacuum related both sides would be doing it and if not that then both O2 sensors on teh same side would be a reading a lean condition.

I guess that I am left with maybe a faulty PCM? It was programmed and it didn't start doing this til the second time that I drove it, I am just stumped any help would be great.
 

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well Mike this falls in the WTF category....

low volt read would mean lean right?

...could swap in a PCM that would be close enough tune for stock just to read O2's...

I don't have the FSM in front of me but if you chased through the diagnostic steps and all checks out..weird.

quite often when we do mods and something comes up after not really related to the mod.....just triple check everything. if it was a rich condition (0152) for me it wound up being cloged CAT...but that is not your deal

Could be a PCM thing...but it could also be a bunch of other stuff

good luck man, wish I could be more help
 

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Discussion Starter · #11 ·
That is cool man, I just went through and ohm all of the O2 sensors out again to make sure they were in their correct locations, since I had them all out. I thought I had checked the wiring last night, but it was 2 am so I think I just thought I did. Anyway, had them connected wrong or mismatched, just ran it and all is good now, thanks for the concern but it turned out to be a dumb mistake on my part, and so everyone that reads this knows, if they aren't connected to the right positions, they won't read right LOL I feel like a dumb ass, oh well sh$% happens.
 

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Discussion Starter · #13 ·
Yeah it was a 4 million things on my mind, trying to get stuff done thing, oh well it is all good. When I threw the new sensor in this afternoon and it did the same thing, it was like a major kick in the balls. But I started searching other forums and google to see what others have done to fix the code, most was change the sensor, well duh did that, there was handful of guys that still have the problem to this day, so got a little worried and said screw it recheck everything :) It panned out a ok. I will tell you that my "customer" is going to be one happy camper with this car it is truly transformed
 
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