P0078

Symptoms

• Unstable engine idling
• Reduced engine power
• Increased fuel consumption
• Check Engine Light Illuminates
• Engine roughness when starting
• Loss of traction when accelerating
• Increased emissions

Causes

• Faulty exhaust valve control solenoid
• Open or short circuit in solenoid wiring
• Oxidized or damaged connector pins
• Engine ECU malfunction
• Solenoid power problems
• Mechanical fault of the phase change system
• Contamination of oil channels of the VVT system

How to Fix

1. Connect the diagnostic scanner and read the error codes
2. Check the condition of the solenoid connector and wiring
3. Measure the solenoid resistance (usually 6-12 ohms)
4. Check for 12V power supply to the solenoid
5. Inspect the solenoid for mechanical damage
6. If necessary, replace the solenoid
7. Check and clean the oil passages of the VVT system
8. Clear error codes and test drive

Related codes

Error P0078 by Vehicle Brand