P0078Exhaust Valve Control Solenoid Circuit Bank 1
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- A solenoid valve on the cylinder head controls oil flow for the variable valve control on the exhaust side of bank 1. Depending on the manufacturer it drives a camshaft phaser (for example on Nissan engines) or a valve lift changeover (for example on Subaru engines). This code family reports electrical faults in its control circuit; P0078 is the general circuit fault: open circuit or short, without distinguishing between them. Some manufacturers use only this code for all electrical faults of the valve. Other manufacturers report the same valve under the "camshaft position actuator" codes instead. Valve control is then switched off or stays in its base position.
- What you may notice
- Check engine light on
- Less power, especially at high engine speed with lift changeover
- Rough idle possible
- Follow-up codes for camshaft timing or misfire possible
- Likely causes
- LikelySolenoid coil open or shorted
- LikelyWiring or connector interrupted, chafed or corroded
- PossibleOil at the connector, e.g. from a leaking valve O-ring
- RareOutput driver or supply in the engine control module faulty
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €50 – €350
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.