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P1238 Fuel Pump Secondary Circuit Malfunction

The OBD2 code P1238 indicates a malfunction in the secondary circuit of the fuel pump, which may involve issues with the fuel pump relay, wiring, or the fuel pump itself, affecting its operation

Definition

The OBD2 code P1238 indicates a malfunction in the secondary circuit of the fuel pump, which may involve issues with the fuel pump relay, wiring, or the fuel pump itself, affecting its operation

Common causes

  • Faulty fuel pump relay
  • Damaged wiring or connectors in the fuel pump circuit
  • Failed fuel pump
  • Faulty fuel pump control module
  • Blown fuse related to the fuel pump circuit
  • Poor ground connection
  • Short circuit in the fuel pump circuit

Common misdiagnoses

  • Fuel Pump Failure
  • Fuel Pump Relay Issues
  • Wiring or Connector Problems
  • Fuel Filter Blockage
  • Engine Control Module (ECM) Malfunction
  • Fuel Pressure Regulator Issues
  • Ignition System Problems
  • Injector Issues
  • Grounding Problems
  • Battery or Charging System Issues

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 the Fuel Pump Relay

    The fuel pump relay controls the power to the fuel pump. Check the relay for proper operation. You can swap it with a similar relay in the fuse box to see if the problem persists

  3. 3. Examine the Fuel Pump Fuse

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

  4. 4. Inspect Wiring and Connectors

    Look for damaged, corroded, or loose wiring and connectors in the fuel pump circuit. Pay special attention to the connections at the fuel pump and the relay

  5. 5. Test the Fuel Pump

    Use a multimeter to check the voltage at the fuel pump connector while the ignition is in the "ON" position. If there is no voltage, the issue may be upstream in the circuit

  6. 6. Check Ground Connections

    Ensure that the ground connections for the fuel pump are secure and free of corrosion. A poor ground can cause circuit malfunctions

  7. 7. Test the Fuel Pump

    If the pump is not receiving power, it may be faulty. You can test the pump by applying direct power to it to see if it operates. If it does not, the pump may need to be replaced

  8. 8. Inspect the Fuel Pressure Regulator

    A malfunctioning fuel pressure regulator can affect the fuel delivery system. Check for proper operation and replace if necessary

  9. 9. Check for Short Circuits

    Inspect the wiring for any signs of short circuits or grounding issues that could cause the secondary circuit to malfunction

  10. 10. Consult Wiring Diagrams

    Refer to the vehicle's service manual for wiring diagrams to trace the circuit and identify any potential issues. 1

  11. 11. Clear the Code and Test Drive

    After performing repairs, clear the code and take the vehicle for a test drive to see if the code returns. 1

  12. 12. Seek Professional Help

    If you are unable to diagnose or fix the issue, consider taking the vehicle to a qualified mechanic or automotive technician for further diagnosis. By following these steps, you should be able to identify and resolve the issue related to the P1238 code