Mercedes-Benz CLK550 coolant fan runs continuously when car is started and remains on after shutdown on Mercedes-Benz CLK550

Some Mercedes-Benz CLK550 owners report experiencing issues with the coolant fan running continuously after starting the vehicle and remaining active even after shutdown. This persistent operation may be attributed to factors such as high temperatures of exhaust gases, transmission oil, or engine coolant. Additionally, owners might face problems related to a malfunctioning coolant temperature sensor or its wiring, a failed fan start relay, damaged drive motor wires, or a malfunctioning electronic engine control unit (ECU). In some cases, the fan may not receive the appropriate signal from the ECU due to issues with the SAM, ECU, or fan controller. Furthermore, continuous fan operation could indicate that the engine is overheating or that the air conditioning condenser is signaling high temperatures, prompting the fan to run at full speed for cooling. It is recommended that affected owners seek a professional diagnosis using specialized tools like SDS before attempting any repairs or replacements.