P0078 Code: Meaning, Causes, and Symptoms | OBD2 Codes

P0078 – Exhaust Valve Control Solenoid Circuit Bank 1


P0078 Possible Symptoms


Engine Light ON (or Service Engine Soon Warning Light)


P0078 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 circuit poor electrical circuit connector


P0078 Description


Exhaust valve timing control magnet retarder controls the shut/open timing of the exhaust valve by ON/OFF pulse duty signals sent from the Engine Control Module (ECM). The longer pulse width retards valve angle. The shorter pulse width advances valve angle.