Hey, have searched and read up as much as I can but still can't find an answer to my question. If anyone can help out any with the following problem would be much appreciated. I have a 01' A3 facelift, 1.6L AVU engine. When I first got the car, the fans would come on seconds after the car was started and remain on after the car was turned off and continue to run untill the battery died. After some forum searching it looked as though my thermostat could be the problem, so I replaced that and why I was at it put in a new temp sensor as well. Put it back together, fans now don't come on, car will heat up to 90deg, fans still don't come on and she continues to heat up. Heater works extremely well, coolant topped up. I have noticed that even when very hot 90+ on the guage, the bottom radiator hose is dead cold along with the radiator, all top hoses very hot. I have checked the radiator to make sure it's not blocked, it's not.. water flows nicely through when checked with the hose. I don't believe the water pump is my problem as it was replaced 5,000km ago and water flows nicely back to the coolant reservoir at any rpm, and my heater works well. Next I thought could my brand new thermostat be the problem (thermostat is the complete housing type with a electronic connection), I have put it in boiling water on the stove for 5minutes and noticed no change .. still completely closed. Did some more forum searching, but am now confused as to whether this thermostat would ever open with just boiling water as I have read it is electronically controlled .. and again read different info telling me the electronic part of the thermostat is just to tell the ECU how hot the car is and to turn on / off the fans.. As such i'm kinda stuck with what to do next, buy another thermostat or do i have an ECU problem? It hasn't thrown any CEL. Sorry for the big first post chasing help , but hopefully this thread will help others in the future.