Genuine OEM Audi Rear Brake Lining Wear Sensor, part number 7L0907637C. This sensor is designed to detect when the brake linings have worn down to a critical level, triggering a warning light to alert the driver for timely replacement. It is installed on the rear brake assembly. This electrical sensor ensures accurate monitoring of brake pad wear. Using a genuine OEM sensor guarantees precise wear detection and reliable communication with the vehicle's onboard systems, crucial for braking safety.