I am working on a family member's 2001 SLK230 and noticed that no matter what temperature the car is running, the overheat light on the analog temp gauge is illuminated. The car does not run over 80C when at operating temperature. All the fluids are topped. I am aware of the coolant level sensor issue, but that sensor has been checked and is functioning. Is this fault with the gauge related to the coolant temp sensor directly connected ot it? Also, where is the gauge coolant temp sensor located on the engine of an '01 M111 motor?