I have a 2005 subaru impreza 2.5 rs. It has about 192k miles on it, but this car has been doing this since I got it from mom I think 2-3 years ago.
When I go interstate speeds, about 55-75mph and I have the heater on while its cold outside, even around 50-45 degree kind of weather, my in dash temp gauge will go up a bit above the 3rd line and will stick there for a while.usuall if I turn the heat off it will go down more quickly. If I keep it on it takes a lot longer for it to go down to normal which is about a smidge above the second line.
I have been told by a horrible mechanic and a great mechanic that temparature gauges in Subarus are faulty amd my car isn't actually running hot at all. So it this true or do I need to replace my thermostat or a sensor? Does anyone else have this problem? This car has never actually overheated and I don't want it to start to.
I recently replaced the head gasket. I've also had the radiator hose retightened because I noticed an antifreeze leak. Nothing else is leaking to my knowledge.