Strange issue with intermittant Temp Sensor Signal, E40 PCM in 2006 GTO(replaced ECM)

[DGS]

You are setting a coolant temp dtc. The fans will go full on, hvac off, and some of your gages will go full on (max) or off (min) so you will notice the fault in case the vehicle is actually over-heating. The reason it returns to normal with a reflash or battery dis-connect is b/c you are clearing the dtc. You need to make sure the dtc's are turned on in your tune for now so you can pinpoint the issue by following the dtc diagnostics. Once you pull you dtc's, you can report back or look up the diagnostic chart for the specific dtc(s). Since you have a tech 2 you can easily pull dtc's. You can turn off your dtc"s , but that's not going to fix you actual issue.

[DGS]

The p0128 is going to set if the temp does not reach a specific temperature rise within a set time period after a cold start. With the lower stat temp, you may have this issue as it's looking for a stock stat in the 180 range. From a cold start though it probably would not be an issue with the colder stat as the time period monitored is less than reaching full operating temp.. This dtc usually sets due to a thermostat that is partially stuck open or has excessive flow when closed thru a hole or by-pass. I would use a GM stat if possible.

[blindsquirrel]

The only way to 'solve' this is to return everything to factory stock so the prediction stuff will be back in range. I think in the previous thread about this he said it wasn't setting any codes.

It sounds like a false detection thing, no harm in killing these 'range/performance' codes. It will still alert to an actual fault through the other codes.

[mm_n_p]

The only way to 'solve' this is to return everything to factory stock so the prediction stuff will be back in range. I think in the previous thread about this he said it wasn't setting any codes.

It sounds like a false detection thing, no harm in killing these 'range/performance' codes. It will still alert to an actual fault through the other codes.

At the time, I did not recall getting a code before i changed out my PCM and only recently noticed that I was, however - I neglected to mention that because at the time I thought the P0128 was a result of my issues, not the cause. Lesson Learned, I will make sure to mention any codes, no matter my assumptions.

With the above said, I have yet to have any issues after disabling the P0128. After all of the research i have done, I want to say that its probably just a slow re-acting thermostat but it was nothing noticeable to me as i'm hyper aware of my gauges and this thermostat has been in the car for a year now. Maybe it has always been on the ragged edge of tripping this code and the installation of nice set of Kooks was enough to send it over...


Edit: - I can't thank everybody enough for all of the help- i was dead set on internal PCM issues or false signals/noise, little did I know that it was all working as designed.

-Steve