The coolant temperature sensor tells the Engine Computer what the temperature is, then the computer turns the fan on when necessary. Other than that, sensors don't cause overheating or other things to happen. They only report what has already happened.
Coolant doesn't circulate through the reservoir like it does in the radiator. All you should see is the coolant level goes up when the engine is hot, and it goes back down when the engine cools down over about an hour or two. You'll see a "hot" and a "cold" mark on the side of the reservoir As long as the level stays between those two points, it's okay.
Saturday, December 20th, 2014 AT 12:40 PM