My 2008 Jaguar XJ while driving after about 45 minutes the temp gauge shows it over heating. I stopped before, no leaks, plenty of coolant, fan working. If I turn on the heat on high and fan on high temp goes down to normal after about 30 seconds, or if I stop and shut car off and start it up again it shows normal, then does it again later. I changed the temp control sensor, and it helped but still does most times, but only after longer driving of about 45 minutes. I need help figuring this out. Thank you

 

Have you checked your thermostat?