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2000 Grand Am O2 Sensor

Marko

TCG Elite Member
Feb 19, 2005
18,799
2,456
Front or rear 02?



Printout from Autozone. I heard it will run rich now too

5e70de95fbb1c8f11b881c36993e7dd8.heic
 

CMNTMXR57

GM, Holden & Chrysler Mini-Van nut swinger
Sep 12, 2008
26,165
31,293
Elgin
You'll be fine. This DTC is the result of the post-cat HO2S being below .400mV for a specified period of time. Usually in the 5 - 10 second window.

With this code, I would start looking at the wiring/connections/terminals/etc first. That is sometimes the issue with this code. Another trick if all wiring checks out and at least tide you over and save a few bucks in the interim, is to remove the sensor, clean it (the part that is in the exhaust stream), with something like a MAF or electronics cleaner, or even brakekleen, reinstall and see if that does it. I bet it's sooted up quite nicely which might be why. After checking the wiring, replacment of the sensor is next on the list IIRC.
 

CMNTMXR57

GM, Holden & Chrysler Mini-Van nut swinger
Sep 12, 2008
26,165
31,293
Elgin
The sensor may actually be fine though. The bulk of the troubleshooting for this diagnostic is wiring issues. Chaffed, worn through, shorting out harnesses. Pulled connectors/terminals, etc. The last step is actual sensor replacement. I think they even recommend to replace the PCM first before the actual sensor in this particular code, which is out of GM's normal step by step process eliminating things from cheapest to most expensive. Usually PCM replacement is the last. So the emphasis is on the wiring here.
 
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