The coolant temperature sensor, as the name shows, is used to indicate the temperature of the coolant in the car. The reason for the exiting of the coolant temperature sensor is for engine running in a proper temperature range. There is a coolant temperature sensor gauge on the instrument panel in your car, and if the indicator shows blue, it's safe. Otherwise, it is overheating. Since the coolant temperature sensor is closely related to the engine working, and the engine will overheating with a malfunctioning sensor. You need to pay more attention on it, and do the regular maintenance. However, the number of the coolant temperature sensor depends, so make sure to read the owner's manual for your BMW car and make a decision. We, with the confidence, are glad to be your first choice and we offer you all BMW genuine OEM coolant temperature sensor with a discounted price.