WOMS
U code network Medium severity

U1279 Invalid or Missing Data for Vehicle Speed

The OBD2 code U1279 indicates that the vehicle's control module has detected invalid or missing data related to vehicle speed, which may affect the performance of various systems

Definition

The OBD2 code U1279 indicates that the vehicle's control module has detected invalid or missing data related to vehicle speed, which may affect the performance of various systems

Common causes

  • Faulty vehicle speed sensor
  • Damaged wiring or connectors
  • Faulty engine control module (ECM)
  • Faulty transmission control module (TCM)
  • Poor ground connections
  • Corroded or damaged connectors
  • Software issues or glitches in the ECM/TCM
  • Issues with the ABS module (if applicable)

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
  • Faulty instrument cluster
  • Issues with the CAN bus communication system

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)

    Locate the vehicle speed sensor and inspect it for any physical damage or disconnection

  3. 3. Check the wiring and connectors for corrosion, fraying, or loose connections

  4. 4. Test the VSS with a multimeter to ensure it is functioning correctly. Refer to the vehicle's service manual for specific resistance values

  5. 5. Examine Wiring and Connectors

    Inspect the wiring harnesses and connectors associated with the VSS and the modules that communicate vehicle speed data

  6. 6. Look for any signs of wear, damage, or poor connections that could affect data transmission

  7. 7. Check the CAN Bus

    Use a scan tool to monitor the CAN bus for any communication issues. Ensure that all modules are communicating properly

  8. 8. Look for any other codes that may indicate a problem with the CAN bus or other modules

  9. 9. Test the Instrument Cluster

    If the vehicle speed data is not being displayed correctly on the instrument cluster, the cluster itself may be faulty

  10. 10. Check for any issues with the cluster's connections and functionality

  11. 11. Inspect the Transmission Control Module (TCM)

    The TCM may also be involved in processing vehicle speed data. Check for any faults or communication issues with the TCM

  12. 12. Check for Software Updates

    Some vehicles may require software updates for the engine control module (ECM) or other modules. Check with the manufacturer for any available updates

  13. 13. Clear Codes and Test Drive

    After performing any repairs or inspections, clear the trouble codes using the OBD-II scanner

  14. 14. Take the vehicle for a test drive to see if the code reappears. Monitor the vehicle speed data during the drive

  15. 15. Consult a Professional

    If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or technician who has experience with your specific vehicle make and model.Conclusion Troubleshooting OBD-II code U1279 involves a systematic approach to identify and resolve issues related to the vehicle speed sensor and communication between modules. By following these steps, you can often pinpoint the problem and take appropriate corrective action