Genuine OEM Volkswagen Knock Sensor, part number 03H905377. This sensor detects engine knocking or detonation and sends a signal to the engine control unit to adjust ignition timing. It is located at position 1 in the diagram. The part weighs 0.065 kg and has dimensions of 0.26m x 0.025m x 0.017m. Genuine OEM knock sensors provide accurate detection of abnormal combustion, ensuring optimal engine performance and preventing damage.