So I've had this issue for pretty much the whole time I've owned the car in that the engine temp gauge rarely reads straight up. Most of the time its between the first and second mark above cold. Tonight I went and logged the engine temp with vagcom and I noticed that except for sitting at long lights the temp stayed from 72°C to 77°C. At lights it would go to 80°C but never above. I replaced the coolant temp sensor back near the firewall last spring but it never seemed to have any impact. Think the thermostat is stuck?

 

Any guesses on it being the coolant temp sensor, thermostat, or something else?

 

Bump...

 

thats not a terrible temp, it should be between 85 and 100 degrees C regardless of where the needle is. if vagcom says its 80* thats not bad. in the summer my car runs 1 mark on the temp gauge hotter then in the winter. when i added my FMIC, it went down one more mark, so it has alot to do with how well the engine is cooled and what the outside temp is. any of those things could cause your engine to run 5* too cold. if you are really worried about it and think theres something wrong, i would be looking at the thermostat.

edit: i misread that, 72C is a bit too cold (160F). thermostat would be my guess. how does your antifreeze look? if its very dirty or not pink and clear like it should be, something could have gotten stuck in the thermostat to hold it open just enough to run a little cold. if you turn your car on when its completely cold, how long does it take to get up to max temperature if you let it sit and idle?