My Thermostat is stuck at cold, never moves no matter how long the engine is running. Also, the Check Engine light has been on. Could these two things be related? It's a 2000 Explorer Sport 4.0L. Could this also be affecting my fuel economy? Any help would be greatly appreciated.

 

Yes, it does affect every thing. It sounds like the sending unit, even with the thermostat stuck open the gauge will still move.