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P code powertrain High severity

P1231 Fuel Pump Secondary Circuit Low High Speed

The OBD2 code P1231 indicates a problem with the fuel pump's secondary circuit, specifically that the circuit is reading low voltage or is not functioning properly at high speed

Definition

The OBD2 code P1231 indicates a problem with the fuel pump's secondary circuit, specifically that the circuit is reading low voltage or is not functioning properly at high speed

Common causes

  • Faulty fuel pump
  • Damaged wiring or connectors
  • Failed fuel pump relay
  • Faulty fuel pump driver module
  • Blown fuse
  • Short circuit in the fuel pump circuit
  • Poor ground connection
  • Malfunctioning engine control module (ECM)

Common misdiagnoses

  • Fuel pump failure
  • Fuel pump relay issues
  • Wiring or connector problems
  • Fuel pressure regulator malfunction
  • Engine control module (ECM) faults
  • Ignition system issues
  • Fuel filter blockage
  • Injector problems
  • Grounding issues
  • Short circuits in the fuel pump circuit

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 for the issue

  2. 2. Inspect the Fuel Pump Relay

    Locate the fuel pump relay in the fuse box and check for any signs of damage or corrosion

  3. 3. Test the relay by swapping it with a similar relay (if available) or using a multimeter to check for continuity

  4. 4. Examine the Fuel Pump Fuse

    Check the fuel pump fuse for continuity. If the fuse is blown, replace it and see if the code returns

  5. 5. Inspect Wiring and Connectors

    Visually inspect the wiring and connectors related to the fuel pump and the secondary circuit. Look for frayed wires, corrosion, or loose connections

  6. 6. Use a multimeter to check for proper voltage and ground at the fuel pump connector

  7. 7. Test the Fuel Pump

    If the wiring and relay are in good condition, test the fuel pump itself. You can do this by applying direct power to the pump to see if it operates

  8. 8. If the pump does not work when powered directly, it may need to be replaced

  9. 9. Check the Fuel Pump Driver Module (if applicable)

    Some vehicles have a fuel pump driver module that controls the operation of the fuel pump. Check for any faults in this module

  10. 10. Test the module for proper operation and replace it if necessary

  11. 11. Inspect the ECM

    If all other components check out, the issue may lie with the engine control module (ECM). Check for any software updates or known issues with the ECM for your vehicle model

  12. 12. In some cases, reprogramming or replacing the ECM may be necessary

  13. 13. Clear Codes and Test Drive

    After performing repairs, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns

  14. 14. Consult a Professional

    If you are unable to resolve the issue after these steps, it may be best to consult a professional mechanic who has experience with your specific vehicle make and model.Additional Tips: - Always refer to the vehicle’s service manual for specific troubleshooting procedures and specifications. - Ensure safety precautions are taken when working with fuel systems, as they can be hazardous. By following these steps, you should be able to identify and resolve the issue related to the P1231 code