P0078 OBD-II: Exhaust Valve Control Solenoid Circuit
P0078 Severity
Should you fix P0078 yourself?
Identifying an OBD code is just the start of a complete diagnostic routine. Most trouble codes are caused by a sensor reporting a value that is out of range. Just replacing a sensor may not fix underlying issues. Be sure to understand the code, the part or system in your car that the code refers to, and the risks of delaying professional repair.
Proper diagnosis will save you time and money on unnecessary repairs.
Urgent codes indicate immediate action is necessary. These are urgent and significant malfunctions that can cause severe damage to the vehicle or harm the driver and passengers.
What causes OBD-II fault code P0078?
The Exhaust Valve Control Solenoid uses oil pressure and an electrical solenoid to control the position of the exhaust valve. Newer vehicles are equipped with variable valve timing (VVT). This allows the engine control module (PCM) to adjust the opening and closing of the exhaust valve to improve fuel consumption while still providing the performance requested by the driver. When the PCM determines there is an issue with the signal from the Exhaust Control Solenoid, the PCM will set code P0078.
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