P0231: Fuel Pump Secondary Circuit Low

Definition

The OBD2 code P0231 indicates that there is a low voltage or an open circuit in the fuel pump secondary circuit, which can affect the fuel pump's operation

Common causes

Faulty fuel pump
Damaged wiring or connectors
Failed fuel pump relay
Blown fuse
Faulty fuel pump driver module
Poor ground connection
Short circuit in the fuel pump circuit
Corroded connectors

Common misdiagnoses

Fuel pump failure
Fuel filter blockage
Wiring issues or shorts
Fuel pressure regulator malfunction
Engine control module (ECM) failure
Relay issues
Grounding problems
Injector problems

Troubleshooting steps

1. Check the Fuel Pump Relay
2. Inspect the fuel pump relay for proper operation. Swap it with a similar relay in the fuse box (if applicable) to see if the problem persists
3. Test the relay with a multimeter to ensure it is functioning correctly
4. Inspect the Fuel Pump Fuse
5. Check the fuse associated with the fuel pump circuit. If it is blown, replace it and see if the code returns
6. Examine Wiring and Connectors
7. Inspect the wiring and connectors leading to the fuel pump and the fuel pump relay for any signs of damage, corrosion, or loose connections
8. Look for frayed wires or broken connectors that could cause a poor connection
9. Test the Fuel Pump
10. Use a multimeter to check the voltage at the fuel pump connector while the ignition is in the "ON" position. You should see battery voltage (around 12V)
11. If there is no voltage, the issue may be upstream in the circuit (relay, fuse, or wiring)
12. Check Ground Connections
13. Ensure that the ground connections for the fuel pump and the relay are secure and free of corrosion. A poor ground can lead to low voltage readings
14. Inspect the Fuel Pump Control Module
15. If your vehicle has a fuel pump control module, check it for proper operation. This may require specialized diagnostic equipment
16. Scan for Additional Codes
17. Use an OBD-II scanner to check for any other related trouble codes that may provide more context for the issue
18. Perform a Voltage Drop Test
19. Conduct a voltage drop test on the fuel pump circuit to identify any resistance in the wiring that could be causing low voltage
20. Check for Fuel Pump Operation
21. If possible, listen for the fuel pump to prime when the ignition is turned on. If you do not hear it, the pump may be faulty
22. Replace the Fuel Pump (if necessary)
23. If all other components check out and the fuel pump is not functioning, it may need to be replaced. 1
24. Clear the Code and Test Drive
25. After performing repairs, clear the trouble code and take the vehicle for a test drive to see if the code returns. If you are not comfortable performing these steps or if the issue persists after troubleshooting, it may be best to consult a professional mechanic for further diagnosis and repair

Definition

Common causes

Common misdiagnoses

Troubleshooting steps

1. Check the Fuel Pump Relay

2. Inspect the fuel pump relay for proper operation. Swap it with a similar relay in the fuse box (if applicable) to see if the problem persists

3. Test the relay with a multimeter to ensure it is functioning correctly

4. Inspect the Fuel Pump Fuse

5. Check the fuse associated with the fuel pump circuit. If it is blown, replace it and see if the code returns

6. Examine Wiring and Connectors

7. Inspect the wiring and connectors leading to the fuel pump and the fuel pump relay for any signs of damage, corrosion, or loose connections

8. Look for frayed wires or broken connectors that could cause a poor connection

9. Test the Fuel Pump

10. Use a multimeter to check the voltage at the fuel pump connector while the ignition is in the "ON" position. You should see battery voltage (around 12V)

11. If there is no voltage, the issue may be upstream in the circuit (relay, fuse, or wiring)

12. Check Ground Connections

13. Ensure that the ground connections for the fuel pump and the relay are secure and free of corrosion. A poor ground can lead to low voltage readings

14. Inspect the Fuel Pump Control Module

15. If your vehicle has a fuel pump control module, check it for proper operation. This may require specialized diagnostic equipment

16. Scan for Additional Codes

17. Use an OBD-II scanner to check for any other related trouble codes that may provide more context for the issue

18. Perform a Voltage Drop Test

19. Conduct a voltage drop test on the fuel pump circuit to identify any resistance in the wiring that could be causing low voltage

20. Check for Fuel Pump Operation

21. If possible, listen for the fuel pump to prime when the ignition is turned on. If you do not hear it, the pump may be faulty

22. Replace the Fuel Pump (if necessary)

23. If all other components check out and the fuel pump is not functioning, it may need to be replaced. 1

24. Clear the Code and Test Drive

25. After performing repairs, clear the trouble code and take the vehicle for a test drive to see if the code returns. If you are not comfortable performing these steps or if the issue persists after troubleshooting, it may be best to consult a professional mechanic for further diagnosis and repair