WOMS
U code network High severity

U0402 Invalid Data Received From Transmission Control Module

The OBD2 code U0402 indicates that the vehicle's control module has received invalid or erroneous data from the Transmission Control Module (TCM)

Definition

The OBD2 code U0402 indicates that the vehicle's control module has received invalid or erroneous data from the Transmission Control Module (TCM)

Common causes

  • Faulty Transmission Control Module (TCM)
  • Wiring issues or damaged connectors
  • Corrupted software or firmware in the TCM
  • Faulty Engine Control Module (ECM)
  • Communication issues between TCM and ECM
  • Low battery voltage or electrical issues
  • Faulty sensors related to transmission operation
  • Poor ground connections

Common misdiagnoses

  • Faulty Transmission Control Module (TCM)
  • Wiring issues or short circuits
  • Faulty Engine Control Module (ECM)
  • Sensor malfunctions (e.g., speed sensors)
  • Transmission fluid issues
  • Poor ground connections
  • Corrupted software or firmware in the TCM
  • Faulty connectors or terminals
  • Issues with the vehicle's CAN bus system
  • Incorrectly installed or damaged aftermarket components

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. Addressing related codes can help pinpoint the issue

  2. 2. Inspect Wiring and Connectors

  3. 3. Visually inspect the wiring and connectors between the ECM and TCM. Look for signs of damage, corrosion, or loose connections

  4. 4. Ensure that all connectors are securely attached and free of dirt or moisture

  5. 5. Check for Software Updates

  6. 6. Verify if there are any software updates available for the ECM or TCM. Manufacturers sometimes release updates to fix known issues

  7. 7. Clear the Code

  8. 8. Clear the U0402 code using an OBD-II scanner and take the vehicle for a test drive to see if the code returns. Sometimes, the code may be a one-time occurrence

  9. 9. Inspect the TCM

  10. 10. If the code persists, further investigate the Transmission Control Module. Check for any signs of failure or malfunction

  11. 11. If possible, test the TCM with a scan tool to see if it is functioning correctly

  12. 12. Check Power and Ground

  13. 13. Ensure that the TCM is receiving proper power and ground. Use a multimeter to check voltage and ground connections

  14. 14. Look for Communication Issues

  15. 15. Use a scan tool to monitor communication between the ECM and TCM. Check for any communication errors or interruptions

  16. 16. If communication is lost, it may indicate a problem with the CAN bus or wiring

  17. 17. Inspect for Fluid Issues

  18. 18. Check the transmission fluid level and condition. Low or contaminated fluid can cause transmission issues that may trigger the U0402 code

  19. 19. Perform a System Reset

  20. 20. In some cases, performing a reset of the ECM and TCM may help resolve communication issues

  21. 21. Consult Technical Service Bulletins (TSBs)

  22. 22. Check for any TSBs related to the U0402 code for your specific vehicle make and model. Manufacturers may have specific recommendations for addressing this code. 1

  23. 23. Professional Diagnosis

  24. 24. If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership. They may have specialized tools and knowledge to diagnose complex issues. By following these troubleshooting steps, you can systematically identify and resolve the underlying cause of the U0402 code