Check Engine Light: A persistent check Saturn VUE Hybrid Engine Control Module light could indicate a problem with the ECU, PCM, or ECM. Use a diagnostic tool to retrieve error codes and identify the issue. Poor Fuel Efficiency: If your car is burning more fuel than usual, the ECU or PCM may need recalibration or reprogramming to optimize fuel delivery. Engine Stalling or Rough Running: A faulty ECM or PCM can cause engine stalling, misfiring, or rough idling. Inspect wiring connections and ...