I'm a newbie here. I have a Y-reg 2.3 petrol Galaxy which is used basically as a wheelbarrow but occasionally for people as well. The other day, the high temp light started flashing with all the usual sound effects. I switched the engine off, checked under the bonnet and all was well. Plenty of water in the header tank, no excessive pressure when I loosened the cap slightly. The guage was registering 90 degrees, which it always does once warmed up. This happened a few times during a 50 mile drive, but not since. I'm wondering if it's the sensor at fault, and if so, is it an easy fix. I'm no wizz-kid mechanic but I do have a bag of spanners and know how to use them. Any advice is more than welcome.