Originally Posted by s4audi12321
Started my 2000 s4 today and the temp gauge started at the half point. And as it warmed up it went to saying it was hot. I checked the water and it's all there and the motor did not seem hot. So is it the sending unit or the thermostat? Help would be great. Thanks
The sensors go bad all the time. If the sensor is more than two years old, replace. They control the ECM. They go bad so often, vag has been extended warranty on them for ten years 100k. If yours is original, you are the luckiest man alive.