WOMS
P code powertrain Medium severity

P1720 Vehicle Speed (Meter) Circuit Malfunction

The OBD2 code P1720 indicates a malfunction in the vehicle speed sensor circuit, which affects the accurate reading of the vehicle's speed

Definition

The OBD2 code P1720 indicates a malfunction in the vehicle speed sensor circuit, which affects the accurate reading of the vehicle's speed

Common causes

  • Faulty vehicle speed sensor
  • Damaged wiring or connectors
  • Poor electrical connections
  • Malfunctioning instrument cluster
  • Faulty engine control module (ECM)
  • Issues with the transmission control module (TCM)
  • Incorrectly calibrated speedometer
  • Mechanical issues with the speedometer drive system

Common misdiagnoses

  • Faulty vehicle speed sensor
  • Wiring issues or shorts in the speed sensor circuit
  • Malfunctioning engine control module (ECM)
  • Incorrect tire size or tire pressure
  • Transmission issues
  • Faulty ABS module
  • Problems with the instrument cluster
  • Poor ground connections

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 Vehicle Speed Sensor (VSS)

  3. 3. Locate the VSS, which is typically found on the transmission or differential

  4. 4. Check for any visible damage, corrosion, or loose connections at the sensor and its wiring harness

  5. 5. Ensure that the sensor is securely mounted

  6. 6. Test the VSS

  7. 7. Use a multimeter to test the resistance of the VSS. Compare the readings to the manufacturer's specifications

  8. 8. If the sensor is a Hall effect type, check for proper voltage output when the vehicle is in motion

  9. 9. Check Wiring and Connectors

  10. 10. Inspect the wiring harness and connectors leading to the VSS for any signs of wear, fraying, or corrosion

  11. 11. Look for any broken or shorted wires that could affect the signal

  12. 12. Examine the Instrument Cluster

  13. 13. If the VSS and wiring are functioning correctly, the issue may lie within the instrument cluster itself

  14. 14. Check for any loose connections or faults in the cluster that could prevent the speedometer from receiving the signal

  15. 15. Inspect the ECM

  16. 16. Ensure that the ECM is functioning properly and that it is receiving the correct signals from the VSS

  17. 17. Check for any software updates or recalls related to the ECM

  18. 18. Test the Speedometer

  19. 19. If applicable, verify that the speedometer is working correctly. A malfunctioning speedometer can sometimes trigger this code

  20. 20. Clear the Code and Test Drive

  21. 21. After performing the necessary repairs, clear the trouble code using the OBD-II scanner

  22. 22. Take the vehicle for a test drive to see if the code reappears

  23. 23. Consult Repair Manual

    If the issue persists, refer to the vehicle's repair manual for specific diagnostic procedures and specifications related to the speed sensor and circuit

  24. 24. Seek Professional Help

    If you are unable to resolve the issue after following these steps, consider consulting a professional mechanic for further diagnosis and repair. By following these troubleshooting steps, you should be able to identify and resolve the cause of the P1720 code