Mercedes-Benz S550 temperature sensor failure causing clicking noise and fan motor issues on Mercedes-Benz S550

Some Mercedes-Benz S550 owners report experiencing clicking noises when starting the car or turning on the AC, which may be attributed to a faulty coolant temperature sensor. This sensor failure can lead to problems with the fan motor, resulting in excessive noise or malfunction. Additionally, a failing coolant temperature sensor may cause a clicking sound from the fuse box, indicating a potential issue. Owners have noted that symptoms of a faulty coolant temperature sensor can include engine overheating, and comparing readings from an infrared temperature monitor with the sensor's output can aid in diagnosis. Furthermore, some owners report that rattling or excessive noise from the radiator fan may stem from a worn motor, debris in the fan blades, or issues related to the coolant temperature sensor or fan control module. It is also advisable to check for a collapsing lower radiator hose that could be causing the motor to "gulp" coolant. Addressing these concerns promptly can help ensure optimal performance and prevent further complications.