P0459: Evaporative Emission System Purge Control Valve Circuit High

Definition

The OBD2 code P0459 indicates a high voltage or an open circuit in the evaporative emission system purge control valve circuit, which can affect the vehicle's ability to control fuel vapors and emissions properly

Common causes

Faulty purge control valve
Wiring issues (shorts or open circuits)
Poor electrical connections
Failed engine control module (ECM)
Vacuum leaks in the evaporative emission system
Faulty fuel tank pressure sensor
Corroded connectors or terminals

Common misdiagnoses

Faulty purge control valve
Wiring issues or shorts in the circuit
Faulty engine control module (ECM)
Vacuum leaks in the evaporative system
Faulty fuel tank pressure sensor
Incorrectly installed or damaged fuel cap
Issues with the evaporative canister
Faulty fuel pump or fuel system components

Troubleshooting steps

1. Check the Code

Use an OBD-II scanner to confirm the P0459 code and check for any additional codes that may provide more context about the issue
2. Visual Inspection
3. Inspect the wiring and connectors associated with the purge control valve for any signs of damage, corrosion, or loose connections
4. Look for any vacuum leaks in the evaporative emission system, including hoses and connections
5. Test the Purge Control Valve
6. Disconnect the purge control valve and test its resistance with a multimeter. Compare the readings to the specifications in the vehicle's service manual
7. If the valve is stuck open or closed, it may need to be replaced
8. Check the Power and Ground
9. With the ignition on (engine off), use a multimeter to check for voltage at the purge control valve connector. You should see battery voltage
10. Check the ground connection for the valve to ensure it is secure and functioning properly
11. Inspect the PCM (Powertrain Control Module)
12. If the wiring and purge valve are in good condition, the issue may lie with the PCM. Check for any software updates or recalls related to the PCM
13. If necessary, perform a PCM reset by disconnecting the battery for a few minutes, then reconnecting it
14. Check for Other Related Issues
15. Inspect the fuel tank pressure sensor and other components of the evaporative emission system for faults
16. Ensure that the gas cap is properly sealed and functioning, as a faulty gas cap can also trigger related codes
17. Perform a Smoke Test
18. If you suspect a vacuum leak, perform a smoke test on the evaporative emission system to identify any leaks that may be affecting the purge control valve operation
19. Clear the Codes and Test Drive
20. After addressing any issues found, clear the trouble codes and take the vehicle for a test drive to see if the code returns
21. Consult a Professional
22. If the issue persists after performing these steps, it may be best to consult a professional mechanic for further diagnosis and repair. By following these steps, you should be able to identify and resolve the issue related to the P0459 code

Definition

Common causes

Common misdiagnoses

Troubleshooting steps

1. Check the Code

2. Visual Inspection

3. Inspect the wiring and connectors associated with the purge control valve for any signs of damage, corrosion, or loose connections

4. Look for any vacuum leaks in the evaporative emission system, including hoses and connections

5. Test the Purge Control Valve

6. Disconnect the purge control valve and test its resistance with a multimeter. Compare the readings to the specifications in the vehicle's service manual

7. If the valve is stuck open or closed, it may need to be replaced

8. Check the Power and Ground

9. With the ignition on (engine off), use a multimeter to check for voltage at the purge control valve connector. You should see battery voltage

10. Check the ground connection for the valve to ensure it is secure and functioning properly

11. Inspect the PCM (Powertrain Control Module)

12. If the wiring and purge valve are in good condition, the issue may lie with the PCM. Check for any software updates or recalls related to the PCM

13. If necessary, perform a PCM reset by disconnecting the battery for a few minutes, then reconnecting it

14. Check for Other Related Issues

15. Inspect the fuel tank pressure sensor and other components of the evaporative emission system for faults

16. Ensure that the gas cap is properly sealed and functioning, as a faulty gas cap can also trigger related codes

17. Perform a Smoke Test

18. If you suspect a vacuum leak, perform a smoke test on the evaporative emission system to identify any leaks that may be affecting the purge control valve operation

19. Clear the Codes and Test Drive

20. After addressing any issues found, clear the trouble codes and take the vehicle for a test drive to see if the code returns

21. Consult a Professional

22. If the issue persists after performing these steps, it may be best to consult a professional mechanic for further diagnosis and repair. By following these steps, you should be able to identify and resolve the issue related to the P0459 code