Mine Did Exactly The Same Fitted A New Sensor Jobs A Good Un Runs Just Under The Middle And Sits There Come Rain Or Shine. When Mine Was Hot Nearly A Needles Width From The Red I Would Open The Bonnett And Didnt Seem Hot So I Changed It. Also I Found That Where The Wire Goes Onto The Sensor It Was Very Loose So I Dont Know If It Was Connecting All The Time Tighted This Up At The Same Time Dont Know If It Was A Coinceidence(speeling) Or Not. But All Good In The Hood Now.

Hope This Helps

Cheers

Ian