I must admit it seems to me to be something like a connection / wiring issue with the run around I seem to be getting as it was only after I changed the temp sensor that the fans started to run continuously.
Another quirk I noticed is that the sensor has four pins but only 3 wires going into it from the plug / socket. the seems to be the stub of a fourth wire in the plug beside the other 3 wires but I can't see a 4th wire. I've pulled back the insulation to see if a 4th wire has snapped but can't find it.
Can anyone confirm that there should only be 3 wires?