i have a 2005 MC and lately the temp gauge is been going pass the middle mark when u turn the car on after a drive and then it comes down. in the past it never reached the middle until last month, fans come on i think at low speed i try unpluging the sensor and gauge weht dead and fans kicked on high. i replaced t-statlast weekend and a few days later after a long drive i found coolant on the floor but it was coming from reservoir. I dont know what else to try or how to chech the temp sensor please help dont want to damage engine

 

You found coolant on the passenger side floor board of the car? If that's the case, the heater core is leaking, usually. Also, when its really hot out, and you have the a/c going, the car will run a little hotter.