Error code
OBD2 P0078
OBD2P0078
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.
What it means
Exhaust Valve Control Solenoid Circuit.
Severity
moderateCan drive, but performance issues may occur.
Summary
P0078 indicates an issue with the exhaust valve control solenoid circuit in bank 1 of your vehicle's engine.
Symptoms
- Check Engine Light (CEL) illuminated
- Rough idle
- Poor performance
- Reduced fuel economy
Common Causes
- Wiring and connector damage due to poor repair practices or rodent damage
- Open circuit in the solenoid coil
Diagnosis
- Check connector and harness for damage
- Test voltage at the solenoid valve while engine is running
- Inspect resistance across solenoid valve pins
Fixes
- Repair or replace damaged wiring and connectors
- Replace faulty exhaust valve control solenoid valve
FAQ
What does P0078 mean?
P0078 indicates a malfunction in the circuit controlling the exhaust valve timing on bank 1 of your engine.
How do I diagnose P0078?
Use a multimeter to check voltage and resistance at the solenoid valve, inspect wiring for damage, and verify connector integrity.
Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.
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