The Genuine BMW Coolant Level Sensor (part number 61318360876) is a sensor designed for use in BMW vehicles to monitor the level of coolant in the engine. It is a genuine OEM (original equipment manufacturer) part, meaning it is made by the same company that produces BMW vehicles. The sensor is responsible for sending signals to the vehicle's computer system to indicate when the coolant level is low, allowing the driver to take necessary action to prevent engine damage. This sensor is essential for maintaining the proper functioning of the engine and ensuring the vehicle's overall performance and longevity.