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P0131 repeating error

EliteSofaYT

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While driving to calibrate the emissions system, we first got a code for low voltage on the 02 sensor, then once that was fixed, a misfire in cylinder 5, and now that that's fixed, we once again get a code for low voltage on the 02 sensor. It doesn't seem to be lacking fuel pressure, as it will get above 4500 RPM easy, as well as above 80 MPH. We replaced all 6 spark plugs, purchased a new coil related to cylinder 5, and try our best to go through the emissions cycle properly, but it just won't happen. It's given this code at the same time as the misfire code. Any thoughts? I want to preserve my Aztek, but at this rate it's pissing me off just to hold the keys.
 

melsg5

Staff member
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Did you use an AC-Deco O2 sensor?
Did you carefully look at the wire harness for any potential internal breaks?
Are you using a scanner that measures real time voltage to the sensor?
Any issues with the coolant temperature sensor?
 

EliteSofaYT

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No, I'm using aftermarket for now, just to get it registered, and I didn't look at the harness. And it's just a basic hand reader that can check I/M readiness. And considering how jacked up the cooling system is, no, I haven't had any issues
 

EliteSofaYT

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To elaborate further on my previous reply

The previous owner had used stop leak on the cooling system, and as a result, I have no heat in my Aztek, lovingly named Buddy.

The O2 sensor has been replaced with a cheapy sensor, just to get it registered, I definitely plan on going back over some things with actual Delco parts.

After me and my brother replaced the 02 Sensor, we cleared the codes and went for a drive, while on the drive, I received a cylinder 5 misfire, after replacing the coil, and the spark plugs on all cylinders, we're back to a low voltage issue on the 02 sensor. I'm taking it to a local Chevy dealer so they can do a proper diagnosis, I have the tools that say "this is the problem" just not the tools that say "this is why the problem is happening" so I know I'm going to pay more for it, but I'm to the point where I just want it done right.
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EliteSofaYT

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Figured out what it was, local mechanic found a specific entry for other GM vehicles with the 3.4 V6 having this repeating code, it turns out to be a faulty/dirty MAF. cleaned it with MAF cleaner and it now functions fine.
 

EliteSofaYT

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Yes, now there should be nothing stopping it from being registered and drivable
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