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PCM possibly going BAD????

Posted: Fri Jul 02, 2021 7:43 am
by bmac
So I've been getting a P1133 code (3 different O2 sensors). I've been logging my drives and I'm pretty sure I've figured out why I'm getting this.

So I'm 99% sure the problem is that according to the log file the MAF readings and upstream O2 Sensor voltage along with a few other things are freezing up (the log data) is showing the same readings for around 20 seconds. So all the voltage and air flow readings aren't changing for that period of time.

Do you guys think my PCM is going bad? Would re-flashing the PCM possibly help? Has anyone ever seen anything like this before?

Pretty much all new sensors and this is the only thing the shop and I can figure. They did say they were going to try and pull a wiring diagram and see if those two were on the same circuit, but they didn't think they were.

Re: PCM possibly going BAD????

Posted: Fri Jul 02, 2021 10:15 am
by AJT2004
Are you using a brand name, GM, Delphi or Denso replacement?
Have you inspected the wiring and connector for damage?

Re: PCM possibly going BAD????

Posted: Fri Jul 02, 2021 12:45 pm
by bmac
I've used Denso, Bosch and Delphi for the O2 Sensor. Currently using the Delphi. I've inspected the wiring and I don't see any problems and It's not like hitting a bump or something causes this, it will occur at any given time, but usually 15-20 minutes into a drive cycle (not every drive). I did go back and look at drive logs from May and I noticed that the freezing was happening then, but for only around 5-10 seconds, so it wasn't triggering a switching error.