WOMS
U code network High severity

U2379 Control Module Communication Bus Off

The OBD2 code U2379 indicates a communication issue where a control module is unable to communicate on the vehicle's communication bus, often due to a fault in the module or wiring

Definition

The OBD2 code U2379 indicates a communication issue where a control module is unable to communicate on the vehicle's communication bus, often due to a fault in the module or wiring

Common causes

  • Faulty control module
  • Damaged wiring or connectors
  • Poor ground connections
  • Communication bus failure
  • Software issues or bugs
  • Corroded terminals
  • Intermittent electrical connections
  • Low battery voltage or power supply issues

Common misdiagnoses

  • Faulty control module
  • Wiring issues
  • Poor ground connections
  • Corrupted software/firmware
  • Faulty sensors
  • Battery or power supply problems
  • Communication network issues
  • Intermittent connection problems

Troubleshooting steps

  1. 1. Check for Other Codes

    Start by scanning the vehicle for any other diagnostic trouble codes (DTCs). Other codes may provide additional context or indicate related issues

  2. 2. Inspect Wiring and Connectors

  3. 3. Visually inspect the wiring and connectors associated with the control modules on the communication bus. Look for signs of damage, corrosion, or loose connections

  4. 4. Pay special attention to the ground connections, as poor grounding can lead to communication issues

  5. 5. Check Power Supply

    Ensure that the control modules have the proper power supply. Use a multimeter to check voltage at the module connectors. If the voltage is low or absent, trace back to the power source

  6. 6. Test the Control Modules

  7. 7. If possible, test the affected control module(s) for functionality. This may involve using a scan tool to check for communication with the module

  8. 8. If the module is not responding, it may need to be replaced

  9. 9. Inspect the Communication Bus

  10. 10. Check the integrity of the communication bus (CAN bus, LIN bus, etc.). Look for short circuits, open circuits, or any other issues that could disrupt communication

  11. 11. Use an oscilloscope or a specialized scan tool to monitor the bus signals for proper voltage levels and waveforms

  12. 12. Check for Interference

    Sometimes, aftermarket accessories or modifications can interfere with the communication bus. Disconnect any non-factory components and see if the issue persists

  13. 13. Perform a Hard Reset

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

  14. 14. Update Software/Firmware

    Check if there are any software updates available for the vehicle's control modules. Sometimes, manufacturers release updates to fix communication issues

  15. 15. Consult Technical Service Bulletins (TSBs)

    Look for any TSBs related to the specific make and model of the vehicle. Manufacturers may have documented known issues and solutions

  16. 16. Seek Professional Help

    If the issue persists after performing these steps, it may be necessary to consult a professional technician or dealership for further diagnosis. They may have access to specialized tools and resources. By following these steps, you should be able to identify and resolve the underlying issue causing the U2379 code