My 2001 Audi TT 180 hp FWD has been operating at low temperatures for quite a while. I have a Scan gauge connected to the diagnostic port and it indicates the temperature to be about 166 Deg. F. The temperature gauge in the car shows the temperature to be at least 1 notch below the center point. Attaining the 166 degree temperature takes about 15 to 20 minutes of driving, which seems somewhat long even though I am driving in an area where the outside temperature is about 60 Deg. F. My first thought was that the problem is the ECT sensor. I recently replaced it, but the low temperature indication is still there. My next thought is that it could be a thermostat, stuck in an open position. What puzzles me though, is that the one time I drove through a hot climate area (110 deg F), my temperature peaked at 206 deg F. I cannot explain this except to assume that the thermostat is behaving erratically and somehow went from an open position to a closed position when it should have obviously stayed open. I would appreciate any suggestions that would help me resolve this problem. The car has only 37K miles on it.