When i search the symptoms for my car i always get the same results, people say i have to replace my thermostat. The problem with my car is that it cools down when i'm going on the highway, the heat seems to be fine in the cabin even at speed but when i've been driving long enough with the coolant not getting warm i get a CEL which is never a good feeling. I've also replaced the coolant temperature sensor but also with no luck. I'm writing here hoping that someone has encountered this strange problem before me and will help me identify the problem so i can have my saab back to full functionality again. To help identify the problem with the car here's some stuff about the car. Both hoses connected to the heater core are warm to the touch, there is no wet spots in the passenger footwell, the fans only come on when the car has been sitting long enough to get to optimal temperature (which it does when it's not moving fast). there is no surge of warm air when revving engine. If anyone knows anything... any help and i mean any would be greatly appreciated.