The Scania DC09 089A is an industrial diesel engine equipped with a Scania‑developed Engine Management System (EMS) that controls fuel injection, EGR, and SCR operations. Common ECU failures include memory corruption leading to “ECU reset” or “communication loss” faults, as well as sensor input errors from crankshaft position or oil pressure sensors causing misfire or idle instability. Typical repair points are the ECU board’s power supply rails, I²C/SPI communication lines, and the diagnostic connector for fault code retrieval. First‑check steps: verify 12 V/24 V supply to the ECU, inspect all wiring harnesses for continuity and corrosion, and read any stored DTCs with a compatible scan tool.[oss-gpt-20b]