Hi there everyone

just after a little advise again. recently the coolant level/temp con has beening coming on. its in red and only seems to happen when the engine is cold (first thing in a morning)
it will stay on for perhaps 20 mins of driving then go out. the level of coolant is fine and the system has no leaks. the operating temp is stable at 90*.
seems to me that it may be a fault sensor but does anyone know which one is favourite??? (1.8t engine code AEB)

cheers.................... mark