Genuine OEM Audi Ignition Transponder Module, part number 4H0909131. This electronic module functions as the reading coil for the vehicle's immobilizer system, detecting the transponder chip in the key to allow engine start. It is an integral part of the ignition system, ensuring vehicle security. This compact module weighs approximately 0.051 kg. Using a genuine OEM transponder module guarantees correct communication with the vehicle's ECU and immobilizer, preventing starting issues and maintaining security.