OBD-II FAULT CODE
P0078
Exhaust Valve Control Solenoid Circuit (Bank 1)
Meaning, symptoms, likely causes, diagnostic checks and repair guidance for P0078.
- Check Engine light
- Poor drivability or reduced fuel economy depending on fault
- Harsh shifting, limp mode, slipping or delayed engagement possible
- Low/dirty transmission fluid
- Solenoid/valve body issue
- Wiring fault
- Internal transmission wear
- Scan all modules and record freeze-frame data before clearing codes
- Check battery voltage and related fuses
- Check transmission fluid level/condition using correct procedure
- Scan TCM data and inspect connector/wiring
- Service/repair fluid or wiring issues first, test solenoid/valve body, seek transmission specialist for internal faults
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Disclaimer: Information is provided for general guidance only and may not apply to all vehicles. Always consult a qualified technician.