I have a 2001 Jetta 2.0.. Last fall it started randomly overheating. Whenever this happened, there would be no heat in the cabin so I parked it for the winter and figured this spring I would replace the thermostat..
Today I replaced the thermostat and it seems to be the same problem. It rises to normal operating temp, hovers for awhile, then begins to slowly max out. Lower hose on the drivers side gets hot, hose running to the thermostat stays cool and I don't feel much pressure in either hose. I am assuming this is my water pump but have been told by others that I need to "burp" the system. I attempted to purge all of the air but I haven't seen any effect.
Also, even when reaching max temp, my radiator fans do not come on. Using VAG-COM i pulled a code P0117 (Engine Coolant Temp Circuit Low). My coolant temperature sensor is maybe 1 year old. Just curious how these would all tie together. Searched around and find mixed "cures". Ideas?