P066F: Cylinder 3 Glow Plug Control Circuit High

Definition

The OBD2 code P066F indicates that there is a high voltage or an open circuit in the glow plug control circuit for cylinder 3, which may affect the glow plug's ability to heat properly for cold starting

Common causes

Faulty glow plug
Open or shorted wiring in the glow plug circuit
Faulty glow plug control module
Poor electrical connections
Blown fuse related to the glow plug circuit
Engine control module (ECM) issues

Common misdiagnoses

Faulty glow plug
Bad glow plug relay
Wiring issues or shorts in the circuit
Faulty engine control module (ECM)
Incorrectly installed or damaged glow plug harness
Fuel system issues
Injector problems
Compression issues in the cylinder

Troubleshooting steps

1. Check for Additional Codes

Use an OBD-II scanner to check for any other related trouble codes. This can provide more context and help identify if there are multiple issues
2. Inspect Glow Plug
3. Remove the glow plug for cylinder 3 and inspect it for damage or excessive wear
4. Test the glow plug with a multimeter to ensure it has the correct resistance (usually around 0.5 to 5 ohms, but check the specifications for your vehicle)
5. Check Glow Plug Relay
6. Inspect the glow plug relay for proper operation. A faulty relay can cause high resistance or prevent the glow plug from receiving power
7. Test the relay by swapping it with a similar relay in the fuse box (if applicable) or using a multimeter
8. Inspect Wiring and Connectors
9. Check the wiring and connectors leading to the glow plug and the relay for any signs of damage, corrosion, or loose connections
10. Repair or replace any damaged wiring or connectors
11. Test Glow Plug Control Module
12. If your vehicle has a glow plug control module, test it to ensure it is functioning correctly. This module controls the operation of the glow plugs and can cause issues if faulty
13. Check Power and Ground
14. Use a multimeter to check for proper voltage at the glow plug connector when the ignition is turned on. You should see battery voltage
15. Ensure that the ground connection for the glow plug is solid and free of corrosion
16. Inspect Engine Control Module (ECM)
17. If all other components check out, the issue may lie with the ECM. Ensure that it is functioning correctly and that there are no software issues or updates needed
18. Clear Codes and Test Drive
19. After performing repairs, clear the trouble codes and take the vehicle for a test drive to see if the code returns
20. Consult Repair Manual
21. Refer to the vehicle's repair manual for specific diagnostic procedures and specifications related to the glow plug system
22. Seek Professional Help
23. If you are unable to resolve the issue after these steps, consider seeking help from a professional mechanic who has experience with diesel engines and glow plug systems. By following these steps, you should be able to identify and resolve the issue related to the P066F code

Definition

Common causes

Common misdiagnoses

Troubleshooting steps

1. Check for Additional Codes

2. Inspect Glow Plug

3. Remove the glow plug for cylinder 3 and inspect it for damage or excessive wear

4. Test the glow plug with a multimeter to ensure it has the correct resistance (usually around 0.5 to 5 ohms, but check the specifications for your vehicle)

5. Check Glow Plug Relay

6. Inspect the glow plug relay for proper operation. A faulty relay can cause high resistance or prevent the glow plug from receiving power

7. Test the relay by swapping it with a similar relay in the fuse box (if applicable) or using a multimeter

8. Inspect Wiring and Connectors

9. Check the wiring and connectors leading to the glow plug and the relay for any signs of damage, corrosion, or loose connections

10. Repair or replace any damaged wiring or connectors

11. Test Glow Plug Control Module

12. If your vehicle has a glow plug control module, test it to ensure it is functioning correctly. This module controls the operation of the glow plugs and can cause issues if faulty

13. Check Power and Ground

14. Use a multimeter to check for proper voltage at the glow plug connector when the ignition is turned on. You should see battery voltage

15. Ensure that the ground connection for the glow plug is solid and free of corrosion

16. Inspect Engine Control Module (ECM)

17. If all other components check out, the issue may lie with the ECM. Ensure that it is functioning correctly and that there are no software issues or updates needed

18. Clear Codes and Test Drive

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

20. Consult Repair Manual

21. Refer to the vehicle's repair manual for specific diagnostic procedures and specifications related to the glow plug system

22. Seek Professional Help

23. If you are unable to resolve the issue after these steps, consider seeking help from a professional mechanic who has experience with diesel engines and glow plug systems. By following these steps, you should be able to identify and resolve the issue related to the P066F code