WOMS
U code network Medium severity

U1237 Module Communication Failure

The OBD2 code U1237: Module Communication Failure indicates that there is a communication issue between the vehicle's control modules, which may prevent them from exchanging data properly

Definition

The OBD2 code U1237: Module Communication Failure indicates that there is a communication issue between the vehicle's control modules, which may prevent them from exchanging data properly

Common causes

  • Faulty wiring or connectors
  • Failed or malfunctioning control module
  • Corroded or damaged pins in connectors
  • Poor ground connections
  • Intermittent electrical issues
  • Software or firmware issues in the module
  • Low battery voltage or weak battery
  • Communication network issues (e.g., CAN bus problems)

Common misdiagnoses

  • Faulty wiring or connectors
  • Defective control module
  • Power supply issues
  • Grounding problems
  • Software glitches or updates needed
  • Intermittent communication issues
  • Other communication protocol failures
  • Sensor malfunctions

Troubleshooting steps

  1. 1. Check for Other Codes

    Use an OBD-II scanner to check for any additional trouble codes. Other codes may provide more context about the issue

  2. 2. Inspect Wiring and Connectors

  3. 3. Visually inspect the wiring and connectors related to the affected module. Look for signs of damage, corrosion, or loose connections

  4. 4. Pay special attention to the wiring harnesses that connect the modules, as these can be prone to wear and tear

  5. 5. Check Power and Ground

  6. 6. Ensure that the affected module has a proper power supply and ground connection. Use a multimeter to check voltage and ground continuity

  7. 7. If the module is not receiving power, trace the wiring back to the fuse box and check for blown fuses

  8. 8. Test the Affected Module

  9. 9. If possible, test the affected module by swapping it with a known good module (if available) to see if the problem persists

  10. 10. If the module is not functioning correctly, it may need to be repaired or replaced

  11. 11. Inspect the CAN Bus

  12. 12. The Controller Area Network (CAN) bus is responsible for communication between modules. Check for any issues with the CAN bus wiring, such as shorts or opens

  13. 13. Use a CAN bus scanner to monitor the communication and check for any abnormalities

  14. 14. Check for Interference

  15. 15. Look for any aftermarket devices or modifications that may interfere with the vehicle's communication network. This includes alarms, stereo systems, or other electronic devices

  16. 16. Reset the Codes

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

  18. 18. Consult Technical Service Bulletins (TSBs)

  19. 19. Check for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance on common communication issues

  20. 20. Professional Diagnosis

  21. 21. 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 with the specific vehicle. By following these steps, you can systematically diagnose and address the U1237 code and its underlying causes