8K0121405Q - Expansion Tank, coolant OE number by AUDI, VAG, VW

OE Number - stands for Original Equipment Number, which refers to the identification number assigned to a complete component or sub-assembly originally installed in a vehicle by the manufacturer. This number helps accurately identify the required part and ensures that it meets the specifications and requirements of the vehicle. The term "Genuine Number" is synonymous with OE Number, denoting the original part number provided by the manufacturer.