WOMS
U code network Medium severity

U1923 U1923: "Module Communication Failure

The OBD2 code U1923 indicates a "Module Communication Failure," meaning there is a problem with communication between vehicle modules, often due to a fault in the wiring, connectors, or the modules themselves

Definition

The OBD2 code U1923 indicates a "Module Communication Failure," meaning there is a problem with communication between vehicle modules, often due to a fault in the wiring, connectors, or the modules themselves

Common causes

  • Faulty wiring or connectors
  • Failed or malfunctioning control module
  • Corrupted software or firmware in the module
  • Poor ground connections
  • Interference from aftermarket devices
  • Low battery voltage or power supply issues
  • Communication network issues (e.g., CAN bus problems)

Common misdiagnoses

  • Faulty wiring or connectors
  • Defective control module
  • Software issues or updates needed
  • Battery or power supply problems
  • Grounding issues
  • Intermittent communication issues
  • Other module failures (e.g., ABS, BCM)
  • Corrupted data or configuration errors

Troubleshooting steps

  1. 1. Check for Other Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. Sometimes, other codes can provide additional context for the communication failure

  2. 2. Inspect Wiring and Connectors

  3. 3. Visually inspect the wiring and connectors associated with the affected module(s). 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 affected module is receiving the proper voltage. Use a multimeter to check the power supply to the module

  6. 6. Test the Module

    If possible, test the affected module to ensure it is functioning correctly. This may involve using specialized diagnostic tools or swapping the module with a known good one

  7. 7. Check for Communication

  8. 8. Use a scan tool to check if you can communicate with the affected module. If you cannot, it may indicate a problem with the module itself or the communication network

  9. 9. Check the communication lines (CAN bus, LIN bus, etc.) for continuity and proper signal levels

  10. 10. Inspect the CAN Bus

    If the vehicle uses a CAN bus system, check for issues such as

  11. 11. Short circuits or open circuits in the CAN wiring

  12. 12. Termination resistors that may be missing or faulty

  13. 13. Interference from aftermarket devices or modifications

  14. 14. Look for Software Issues

    Sometimes, a software glitch can cause communication failures. Check if there are any available software updates for the affected module(s) and apply them if necessary

  15. 15. Reset the Modules

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

  16. 16. Consult Technical Service Bulletins (TSBs)

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

  17. 17. Professional Diagnosis

    If the issue persists after performing the above steps, it may be necessary to seek assistance from a professional mechanic or dealership with advanced diagnostic equipment. By following these steps, you can systematically identify and resolve the underlying cause of the U1923 code