WOMS
U code network Medium severity

U1639 Invalid or Missing Data for Vehicle Speed

The OBD2 code U1639 indicates that there is invalid or missing data related to the vehicle speed, which may affect the vehicle's performance or systems that rely on speed information

Definition

The OBD2 code U1639 indicates that there is invalid or missing data related to the vehicle speed, which may affect the vehicle's performance or systems that rely on speed information

Common causes

  • Faulty vehicle speed sensor
  • Damaged wiring or connectors
  • Poor ground connection
  • Malfunctioning engine control module (ECM)
  • Issues with the transmission control module (TCM)
  • Faulty ABS module
  • Corrupted data communication between modules
  • Software glitches or updates needed in the vehicle's computer system

Common misdiagnoses

  • Faulty Vehicle Speed Sensor (VSS)
  • Malfunctioning Engine Control Module (ECM)
  • Wiring issues or short circuits in the speed sensor circuit
  • Faulty ABS module
  • Incorrect tire size or calibration issues
  • Transmission problems
  • Issues with the instrument cluster
  • Faulty or corroded connectors in the speed sensor 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. Codes related to the transmission, speed sensor, or other modules can provide additional context

  2. 2. Inspect Vehicle Speed Sensor (VSS)

  3. 3. Locate the VSS and inspect its wiring and connectors for damage, corrosion, or loose connections

  4. 4. Test the VSS for proper operation using a multimeter or oscilloscope. Compare the readings to the manufacturer's specifications

  5. 5. Examine Wiring and Connectors

  6. 6. Check the wiring harnesses and connectors associated with the VSS and any related modules (e.g., Engine Control Module, Transmission Control Module)

  7. 7. Look for frayed wires, broken connectors, or signs of short circuits

  8. 8. Check for Ground Issues

    Ensure that all ground connections related to the VSS and the modules communicating with it are secure and free of corrosion

  9. 9. Inspect the CAN Bus

    Since U1639 is a communication code, check the Controller Area Network (CAN) bus for faults

  10. 10. Look for any damaged wiring or loose connections in the CAN bus

  11. 11. Use a scan tool to monitor the CAN bus for proper communication between modules

  12. 12. Test the Instrument Cluster

    If the vehicle speed data is not being displayed correctly on the instrument cluster, the cluster itself may be faulty. Check for any issues with the cluster's internal circuitry

  13. 13. Check for Software Updates

    Sometimes, a software update for the vehicle's modules can resolve communication issues. Check with the manufacturer or a dealership for any available updates

  14. 14. Perform a Hard Reset

    Disconnect the vehicle's battery for a few minutes to reset the modules. Reconnect the battery and see if the code reappears

  15. 15. Consult Technical Service Bulletins (TSBs)

    Look for any TSBs related to the U1639 code or vehicle speed sensor issues for your specific make and model. Manufacturers may have known fixes for common problems

  16. 16. Professional Diagnosis

    If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership. They may have specialized diagnostic tools and experience to pinpoint the problem. By following these steps, you should be able to identify and resolve the issue related to the U1639 code