WOMS
U code network Medium severity

U1656 Invalid or Missing Data for Vehicle Speed

The OBD2 code U1656 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 U1656 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
  • 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 control modules

Common misdiagnoses

  • Faulty Vehicle Speed Sensor (VSS)
  • Wiring issues or shorts in the speed sensor circuit
  • Malfunctioning Engine Control Module (ECM)
  • Incorrectly calibrated speedometer
  • Faulty ABS module
  • Issues with the transmission control module (TCM)
  • Problems with the CAN bus communication
  • Faulty wheel speed sensors
  • Incorrect tire size or pressure affecting speed readings
  • Software glitches in the vehicle's computer systems

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, ABS, or other systems may 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. Check Wiring and Connectors

  6. 6. Inspect the wiring harnesses and connectors associated with the VSS and the modules that communicate vehicle speed data (e.g., Engine Control Module (ECM), Transmission Control Module (TCM))

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

  8. 8. Test the Communication Network

  9. 9. Use a scan tool to monitor the communication between modules. Check if the ECM and TCM are receiving and sending data correctly

  10. 10. Look for any communication issues on the CAN bus or other communication networks in the vehicle

  11. 11. Inspect the Instrument Cluster

  12. 12. If the vehicle speed is displayed incorrectly on the dashboard, the issue may lie within the instrument cluster. Check for any faults or malfunctions in the cluster

  13. 13. Check for Software Updates

  14. 14. Sometimes, software glitches can cause communication issues. Check with the manufacturer for any available software updates for the vehicle's modules

  15. 15. Clear Codes and Test Drive

  16. 16. After performing any repairs or inspections, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code reappears

  17. 17. Refer to the vehicle's service manual for specific diagnostic procedures and specifications related to the VSS and communication protocols

  18. 18. Professional Diagnosis

  19. 19. If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership with experience in diagnosing OBD-II codes and vehicle communication issues. By following these steps, you should be able to identify and resolve the underlying cause of the U1656 code