Possible causes – Faulty Exhaust Valve Timing Control Magnet Retarder– Exhaust Valve Timing Control Magnet Retarder harness is open or shorted– Exhaust Valve Timing Control Magnet Retarder poor electrical circuit connector When is the obd code mean? An improper voltage is sent to the Engine Control Module (ECM) through exhaust valve timing control magnet retarder….