Hershey, where is this temp sensor located? Do I need to drain cooling system to change it? ThanksThe fan comes on at startup regardless if the fan sensor is good or not, the fan is controlled by a relay the sensor kicks on. I had a boil over when new because the fan sensor was bad. You need to verify fan is operational during use. I have a small sharpie dot on the dash screen over temp guage where the needle gets to when the fan sensor kicks. Your temp guage should never get to halfway mark.Wile using it and you see temp gauge high, simply turn off then restart and as the fan kicks on at startup you will see the needle drop quick. I had to do that until my sensor arrived, dealer mailed it to me under warranty.