For the past couple months my TT has been showing some strange coolant temp. fluctuations. When I'm cruising on the highway the coolant temp falls from operating (90C) to about 70-75C. When I am city driving the temperature is usually ok. I have got the thermostat replaced about a year ago and it was checked recently. There are no fault codes showing up as well. I also had the guage cluster replaced last year on warranty and the time/date is resetting again. So it could be the gauge cluster again i suppose.
Does anyone know if there is another problem that would cause this? Does a coolant temperature sensor malfunction sometimes not show up as a fault?
Yes, my mechanic said that it is acting exactly like a broken thermostat. But he said the thermostat was fine. If it was the sender wouldn't it create a fault for the VAG to read? Also, which sender would it be isn't there a G2 and G62?
I don't have a TT schematic, but the temperature sender P/N 059 919 501A has both temp gauge and fuel injection sensors in one unit. I looked this up for a 2000 TT, please check on your own to be sure that you get the correct part.