Genuine OEM Audi Engine Control Unit, part number 4E0910559H. This unit is the central computer for the engine, responsible for managing fuel injection, ignition timing, and other critical functions to optimize performance and emissions. It is typically located in the engine bay. This component is vital for precise engine operation. Genuine OEM ECUs are programmed with the exact specifications and firmware required for the vehicle's engine, ensuring optimal performance, reliability, and emissions compliance.