Genuine OEM Audi Engine Control Unit, part number 04L906021BT. This control unit is essential for managing various diesel engine functions, including fuel injection, ignition timing, and emissions control. It is typically located within the engine bay or passenger compartment. The precise calibration and integrated circuitry of a genuine OEM unit ensure optimal engine performance, fuel efficiency, and compliance with emissions standards. Genuine OEM control units are manufactured to exact specifications for reliable operation and longevity.