I have been looking at this car today for a colleague. Just recently the temp gauge has been acting slightly weird and just jumping from cold to 90. Then on Sunday night the MIL came on. He had it towed to our work and I scanned it and found the code above.
I have done some basic checks on the temp sensor, i.e resistance checks and voltage across the 2 wires going into it. It all seems to be normal. I have also cleaned up the terminals and made sure the plug was fitted securely. I then erased the code and all was well for a while. Then after a couple of short journeys the MIL came back on when he had just parked it up. I wasn't able to test the sensor at that point as I wasn't with the car at the time. So I then did another scan today, and found the same fault code. I cleared the code and ran the car trying to get the MIL to come back on again so I could test the sensor to see if that is causing the light to come on, but the light stayed out.
Has anyone come across this before and if so what is the remedy for it? Also, am I missing something in my test results as I think they look pretty normal. I don't have live data for it as my diagnostic kit isn't that thorough I'm afraid.
Sensor resistance 21c - 3400 ohms
Sensor resistance 76c - 230 ohms
voltage across sensor 21c - 3.7v
voltage across sensor 76c - 2.3v.
My next test which I will do is to test the wiring from the ECM but thought I would ask for some advice over what I have done already.
Thanks in advance as always for any advice given.