Check Engine Light: 01 Pontiac Aztek Help

TollKeeper

Original poster
Supporting Donor
Member
Dec 3, 2011
8,047
Brighton, CO
I know, I know.. Its a Pontiac Aztek. But its my wifes car, and my son also travels in the car with her, so I got to keep it running top notch.

So 2 weeks ago, SES light pops on, pull the code, I dont remember exactly (it was 2 weeks ago), but I think it was P0131, B1S1 O2 sensor. At that time I did not have a scantool to look at live data.

I ordered a new ACDelco O2 sensor, installed it last week, clear the SES light. And assume all is good. I also ordered a TOPDON Elite scantool.

Took the truck out yesterday, and the SES light comes on again. I got code P0131 B1S1 o2 sensor. I run the live data on it, which I will admit I am not very good at understanding the data, but the data, from articles I have read, are very consistant of what the O2 sensor should be doing. STFT look good, again from my understandings. I look at the rear o2 sensor, and the data stream looks very slow. Going to one voltage, 0.665 and staying there for a long time, than dropping to 0.140 and staying there for a long time. Rinse and repeat.

I plugged my Scantool into my Envoy for comparisons sake, and I have 2 rear o2's on it. One sensor looks to be moving around fairly quickly, going from 0.145 up to 0.720 fairly regularly and consistently. The other bank, not so much. hanging mostly around 0.620 with slight deviations, but not very much. The front 02 sensors are operating in what I believe are in normal fashion, with very regular and consistent movement from 0.060 up to 0.800.

So on my Aztek, why would I be getting a code for B1S1 when it appears to be operating normal? What else should I be checking? Could the rear o2 sensor be causing a check engine light for the front o2 sensor?

On my Envoy, considering the mileage this truck has, and these are still factory o2 sensors, I am not complaining. But it does look like I might need to replace a rear o2 sensor in the future, although for the moment, no SES light, and fuel mileage seems good.

Suggestions and other input? (working on the Aztek now)
 

Chickenhawk

Member
Dec 6, 2011
779
Rear O2 sensors should read very steady. They are there only to gauge how well the cat convertor is performing.

Front O2 sensors should jump very frequently (several times a second) from .1 to .9 volts.

Generally, trouble codes don't point at causes; they point at symptoms. Your sensor could be getting a low voltage reading from a number of causes, including improper fuel mixture. What is your coolant temperature reading when warm?
 

TollKeeper

Original poster
Supporting Donor
Member
Dec 3, 2011
8,047
Brighton, CO
I don't remember what it said on the Livestream, but I do remember my temp gauge was reading the normal operating temp on both cars.
 

TollKeeper

Original poster
Supporting Donor
Member
Dec 3, 2011
8,047
Brighton, CO
I reran the test last night, and watched the livestream. ECT was started at 193, and ended at 197. O2 sensor voltage was doing what I consider to be normal up and down spikes, STFT were floating around 2.2 to 3.97 at idle. Rear O2 sensor readings started with spikes (when engine was much colder, 95ish degrees), I ran the engine up to NOT (normal operating temp), and watched the data stream again, and it had leveled off, and was staying in the 0.555 to 0.637 range fairly consistently.

The Aztek forum is telling me to just drive it for 100 miles, and it should clear it self out. But for some reason, I am not buying it.

It had 3 readiness test passes. 5 readiness test fails. 4 Readiness tests not complete. I can buy the readiness tests not complete. My wife, the primary driver, does very short drives, 1-5 miles, with most frequent drives of 1 mile. the other 3 and 5 were probably me driving it on Saturday, where we went on a 30 mile drive for lunch, and promptly got sick, and went back home.

I really need to figure out how to get the datastream recording off the device, but have not figured it out yet.
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
I think the way to do it is to record the screen. @Blckshdw posted that he uses the Mobizen app.
 
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