The Genuine Audi Disc Brake Pad Wear Sensor - 420615437 is a component used in Audi vehicles to monitor the wear of the brake pads. It is a small electronic sensor that is attached to the brake pad and measures the thickness of the pad. When the brake pad reaches a certain level of wear, the sensor will send a signal to the car's dashboard, alerting the driver that it is time to replace the brake pads. This sensor helps to ensure that the brake pads are replaced before they become too worn, which can lead to decreased braking performance and potential safety hazards. The Genuine Audi Disc Brake Pad Wear Sensor - 420615437 is a genuine OEM part and is designed specifically for use in Audi vehicles. It is a reliable and accurate tool for monitoring brake pad wear and ensuring optimal braking performance.