WOMS
P code powertrain Medium severity

P0079 Exhaust Valve Control Circuit Low (Bank 2)

The OBD2 code P0079 indicates a malfunction in the exhaust valve control circuit for Bank 2, specifically signaling that the circuit is operating at a low voltage or is not functioning properly

Definition

The OBD2 code P0079 indicates a malfunction in the exhaust valve control circuit for Bank 2, specifically signaling that the circuit is operating at a low voltage or is not functioning properly

Common causes

  • Faulty exhaust valve control solenoid
  • Wiring issues (shorts, opens, or corrosion)
  • Poor electrical connections
  • Failed engine control module (ECM)
  • Vacuum leaks
  • Faulty exhaust camshaft timing mechanism
  • Malfunctioning variable valve timing (VVT) system
  • Blocked or restricted exhaust system

Common misdiagnoses

  • Faulty camshaft position sensor
  • Faulty crankshaft position sensor
  • Ignition system issues
  • Fuel delivery problems
  • Vacuum leaks
  • Wiring or connector issues
  • Faulty engine control module (ECM)
  • Incorrectly diagnosed valve timing issues
  • Misinterpreted symptoms related to other engine codes
  • Exhaust system blockages

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. This can provide more context and help identify related issues

  2. 2. Inspect Wiring and Connectors

  3. 3. Visually inspect the wiring and connectors associated with the exhaust valve control solenoid for any signs of damage, corrosion, or loose connections

  4. 4. Pay special attention to the wiring harness for fraying or breaks

  5. 5. Test the Exhaust Valve Control Solenoid

  6. 6. Use a multimeter to check the resistance of the solenoid. Compare the readings to the specifications in the vehicle’s service manual

  7. 7. If the solenoid is not within specifications, it may need to be replaced

  8. 8. Check Power and Ground

  9. 9. Verify that the exhaust valve control solenoid is receiving the correct voltage and ground signal. Use a multimeter to check for power at the connector while the ignition is on

  10. 10. If there is no power, trace the circuit back to the engine control module (ECM) to identify any issues

  11. 11. Inspect the VVT System

  12. 12. Check the operation of the variable valve timing system, including the timing chain/belt and any associated components

  13. 13. Ensure that the timing is set correctly and that there are no obstructions or mechanical failures

  14. 14. Check Engine Oil Level and Condition

  15. 15. Low or dirty engine oil can affect the operation of the VVT system. Ensure that the oil level is adequate and that the oil is clean

  16. 16. Clear Codes and Test Drive

  17. 17. After performing any repairs or replacements, clear the trouble codes and take the vehicle for a test drive to see if the code returns

  18. 18. Refer to the vehicle’s service manual for specific diagnostic procedures and specifications related to the exhaust valve control circuit

  19. 19. Seek Professional Help

  20. 20. If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who has experience with the specific make and model of the vehicle. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the P0079 code