Genuine OEM Volkswagen Diesel Engine Control Unit, part number 05L906022JR550. This unit is the brain of the diesel engine, responsible for managing fuel injection, ignition timing, and emissions control systems. It is typically located in the engine bay. The unit weighs approximately 0.986 kg and has dimensions of 0.21m x 0.185m x 0.04m. Genuine OEM engine control units are critical for ensuring the correct firmware and sensor calibration, which is essential for reliable engine operation and emissions compliance.