Hi folks, just trying to get a bit of help with my temp sensor... I have an Audi A4 B5 1999 Treg Saloon 1.8 non turbo 5V and its petrol (think thats everything lol) Basically is the Dial on the temp gauge suppose to be at 90 deg and stay at 90 deg even when your driving? If i stay still and dont have the heaters on it will rise to 90 and stay there, go no further (good thing) but when i drive it goes down gradually and read at it lowest point as if the engine is switched off within about 10 - 20 mins, the same if i put warm air into the car Now in my experience isn't it suppose to stay reading 90deg Celsius wether the car is standing still or moving? i can probably understand if it dropped because i had the eaters on MAX and full fan speed Can anyone shed any light on this for me as its bugging me a bit now... I do get hot air.. very hot but if the temp gauge is below 90 doesn't the ecu tell the engine its cold and runs more fuel to (try) get it hotter? This had been bugging me for a few years now, would changing the thermostat solve the problem?