02 sensor

LynnM

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#1
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MAKE:Buick
MODEL LaSabera
YEAR:2002
MILES:66K 3.8
DESCRIBE ISSUE....Code p0134 No activity bank 1 sensor 1
Replaced O2 sensor twice same code comes back within 10 miles. had mechanic check wiring ?No luck any ideas ???? computer ? where is it ? kick panel ?
 
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#2
There are NO other codes?
You have checked heater circuit - 12v?
With a scanner What is the PCM showing as sensor V voltages?
spray carb cleaner or richen mixture see if sensor reacts - V goes higher.
Create a vac leak see if V goes lower.

PS B1S1 is rear manifold sensor...
 

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billr

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#3
Check (sensor) heater circuit current. Check sensor voltage right down at its connector to the harness; both connected and disconnected from harness.
 
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#4
O2 sensor constantly gets blamed when the real problem is an engine misfire due to ignition or an injector. Cylinder misfires putting excess oxygen into the exhaust so the sensor cannot switch.

Other problems are electrical in nature, namely, when you hit the starter, if the voltage drops below 8.8 V, all those computers do not get a proper power on reset, microcontroller needs it program counter to be reset to zero to start reading code from the beginning. and since this microcontroller is also used to diagnose itself, no telling what kind of codes you will get.

In one vehicle, the electronic dash would not light up for my father-in-law, dealer told him he needs a new dash for $$$$$, was not the problem ignition switch had dirty contacts. Or a poor ground or excess resistance anywhere in the positive voltage size, like a corroded fuse or in the battery terminal itself. Another, the radio would not work, or an electrically heated thermostat, or poor contacts in a point contact relay. 89 Continental the electronic suspension was the weak point, this list goes on and on, every vehicle is different. But all the same, because the EPA determines how a vehicle must be made.

Ha, should advertise, if you want problems, we got problems. Use to use all pretinned wire, now bare copper crimped, copper oxidizes and becomes a good insulator creating excessive voltage drops the computers do not get.

We would be dead without a scope, never see one at any shop.
 

LynnM

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#5
Mechanic said 4.5 Volts ? and not changing. I was pissed he had the car from Wed until Monday afternoon So where is the computer located.. Thank you
It's just that the last few months I have been broken into twice last time they took my 30 gal compressor and all my air tools. It's just a F U world anymore
 

billr

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#6
4.5V on what? The sensor signal should be 0 to 1V, no way could you get 4.5V from it. The threshold is .45V (450 millivolts), maybe that's what he said/meant; but it is unlikely it would get stuck right at that "knife-edge" threshold. Was that a measurement via live-data, or taken with a meter down at the O2 sensor as suggested in my reply #3?

The sensor heater should have battery voltage, about 12V. Again, measuring current in that heater circuit may be more useful.
 
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#7
AGree with bill, likey its .450v.
Also .450 is exactly a voltage used by computer, Its the bias V, something like a open loop cold start guesstimate till sensor reports.
Try forcing mixture rich or lean, if it will not change then the sensor hi and low reference (TAN PPL) are shorted.
Did you use a aftermarket - wire yourself o2 sensor? They are problematic akin to one size fits all as well as wire color mix matches.

PCM in underhood beneath air cleaner box... I doubt PCM has failed.
 

LynnM

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#8
Probably was .45 I was not in the mood for the BS.. I had left the car with the mechanic On Wed and went to pick it up on the following Monday PM It was not fixed and he didn't have a clue.
I thought it should be looked at by mechanic as it was beyond my ability .
My shop has been broken into twice in the last few months. Last time they even took my 5 HP compressor and all of my air tools
 

nickb2

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#9
Ok, somehow this thread got by me. If the 02 on that car is reporting
Code p0134 No activity bank 1 sensor 1
The best thing to do now is back probe, because after two new
Replaced O2 sensor twice same code comes back within 10 miles
Your words mind you, something is not right here.
 
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nickb2

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#10
Lynnm, we have talked before to your good joy if I remember. Now the only thing you need to do is keep a cool head and focus on the problem.

You need to connect a 3amp protected jumper before condemning the PCM, which in my opinion would be a costly mistake.

You want to see a high and low signal reporting back from at least one of the 2 new sensors you replaced. So obviously, that is not where the problem lays.

Here is a chart, for your trouble shoot, if for some reason you are at step 12 of the following pdf, make sure all steps have been followed, and then you can safely replace the pcm. But that is always a last ditch effort, and most times, not the problem.

Ground checks are very important, as GM has been known for such issues, especially thier PCM connections seem to turn to dust.

Now this is very important for you to understand. If the PCM is supplying a 0.45v ref, that is your pcm telling you the circuit is short or open and just giving what it should be doing by mode of fail safe.

The PCM gives a bias voltage.
 

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nickb2

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#11
So essentially, what I am trying to explain in my awkward english is that your PCM/ECU is in limp in mode right now and giving a bias of 0.45v.

So to cool down your head, listen to this video, it may help you more understand what your local mechanic is missing.

Live data is a must here and some good sound reasoning logic along side a multi-meter.

Watch this video for more info.

Live data is a must.

 

LynnM

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#12
Fixed ! broken sensor wire. GM made to fail crap !!! in the harness where it goes into the air box
 

billr

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#15
So, the air-flow caused the harness to flap around enough that a wire fatigued and broke? Or, the air-flow eroded the harness and wiring insulation away and caused a short? I'm still not understanding what the actual failure was.