WOMS
P code powertrain Medium severity

P1642 Fuel Pump Monitor Circuit High Input

The OBD2 code P1642 indicates that the fuel pump monitor circuit has detected a high input signal, which may suggest a malfunction in the fuel pump circuit or related components

Definition

The OBD2 code P1642 indicates that the fuel pump monitor circuit has detected a high input signal, which may suggest a malfunction in the fuel pump circuit or related components

Common causes

  • Faulty fuel pump relay
  • Short circuit in the fuel pump monitor circuit
  • Open circuit in the fuel pump monitor circuit
  • Faulty fuel pump
  • Malfunctioning engine control module (ECM)
  • Corroded or damaged wiring/connectors
  • Faulty fuel pump driver module

Common misdiagnoses

  • Faulty fuel pump
  • Fuel pump relay issues
  • Wiring or connector problems
  • Engine control module (ECM) failure
  • Fuel pressure regulator malfunction
  • Incorrect fuel level sensor readings
  • Faulty ignition switch
  • 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 and help identify related issues

  2. 2. Inspect Wiring and Connectors

  3. 3. Visually inspect the wiring and connectors associated with the fuel pump and the fuel pump monitor circuit. Look for signs of damage, corrosion, or loose connections

  4. 4. Pay special attention to any frayed wires or broken connectors that could cause a high input signal

  5. 5. Test the Fuel Pump Relay

  6. 6. Check the fuel pump relay for proper operation. A faulty relay can cause incorrect voltage readings

  7. 7. Swap the relay with a similar one (if available) to see if the code clears

  8. 8. Check the Fuel Pump

  9. 9. Test the fuel pump for proper operation. A malfunctioning fuel pump can lead to incorrect readings in the monitor circuit

  10. 10. Measure the voltage at the fuel pump connector while the engine is running to ensure it is receiving the correct voltage

  11. 11. Inspect the Fuel Pump Monitor Circuit

  12. 12. Use a multimeter to check the voltage and resistance in the fuel pump monitor circuit. Compare the readings to the specifications in the vehicle’s service manual

  13. 13. Look for any shorts to ground or open circuits that could cause a high input signal

  14. 14. Check the Fuel Level Sensor

  15. 15. If applicable, inspect the fuel level sensor for proper operation. A faulty sensor can send incorrect signals to the engine control module (ECM)

  16. 16. Examine the Engine Control Module (ECM)

  17. 17. If all other components check out, the issue may lie with the ECM itself. Check for software updates or reprogramming if necessary

  18. 18. Ensure that the ECM is receiving the correct signals from the fuel pump monitor circuit

  19. 19. Clear the Code and Test Drive

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

  21. 21. Consult a Professional

  22. 22. If you are unable to diagnose or resolve the issue, it may be best to consult a professional mechanic who has experience with OBD-II systems and can perform more advanced diagnostics. By following these steps, you should be able to identify and resolve the issue related to the P1642 code. Always refer to the specific service manual for your vehicle for detailed information and specifications