Genuine OEM Volkswagen Engine Control Unit, part number 3G0906259AD. This unit is the brain of the engine, responsible for managing all critical functions such as fuel injection, ignition timing, and emissions control. It is typically located in the engine bay or passenger compartment. The unit weighs approximately 0.918 kg and has dimensions of 0.185m x 0.18m x 0.045m. Genuine OEM ECUs are essential for correct firmware and sensor calibration, ensuring reliable engine operation and compliance with emissions standards.