Mario man, if the car was overheating, you would be able to tell... Trust me. Have you checked your Coolant levels since you put it in? Check your Oil for Coolant too... Check the exaust for snow white smoke, though if you saw this the gasket it severly [censored].
If the level is the same, than I would say that it's OK. Gotta fix that sensor man. Do you know where it is? It is not that expensive...
