For the past year I get engine fault code P0115 "Engine Coolant Temperature Circuit Malfunction" when I head into the mountains to go skiing. The check engine light appears as the temperature drops and stays on until I clear the code when I get home. Then I don't get the error message again until I head into the mountains again. Any ideas? And where is the Engine Coolant Termperature Sensor in a W210 4Matic Wagon?