My audi tt is overheating, the temp gage is fluctuatig rapidly from normal to hot and then back to normal? I have replaced the sensor, modular and electric water pump. Has anyone else ever had this problem?

 

The coolant temp sensor on the engine or in the side of the radiator? Whichever you changed, do the other too. The one on the engine drives the gauge and feeds to the ECU and the one on the radiator controls the cooling fan. If neither fixes it, you may have a bad thermostat. Does the lower radiator hose get hot like the upper? If the thermostat works right it should.

 

The coolant temp sensor on the engine or in the side of the radiator? Whichever you changed, do the other too. The one on the engine drives the gauge and feeds to the ECU and the one on the radiator controls the cooling fan. If neither fixes it, you may have a bad thermostat. Does the lower radiator hose get hot like the upper? If the thermostat works right it should.