I know its only been 8 days I left my car sitting in the carpark, but when I came back from holidays the temp guage has gone mad! outside was about 18 degrees but the indicator showed 38, and then the next day it climbed to the 40s and then 50s and as soon as it hit 60 degrees on the 3rd day it died on me... now it doesnt show the temp at all! any ideas whats happening?