WOMS
U code network Medium severity

U1305 U1305: "Module Communication Failure

The OBD2 code U1305 indicates a communication failure between modules in the vehicle's network, suggesting that one or more electronic control units (ECUs) are not communicating properly

Definition

The OBD2 code U1305 indicates a communication failure between modules in the vehicle's network, suggesting that one or more electronic control units (ECUs) are not communicating properly

Common causes

  • Faulty wiring or connectors
  • Failed control module
  • Poor ground connections
  • Corroded terminals
  • Short circuits in the communication lines
  • Intermittent electrical connections
  • Software issues or bugs in the modules
  • Low battery voltage or weak battery
  • Incompatible or aftermarket modules installed
  • Communication network issues (e.g., CAN bus problems)

Common misdiagnoses

  • Faulty wiring or connectors
  • Defective control modules
  • Battery or charging system issues
  • Grounding problems
  • Software or firmware issues
  • Intermittent electrical connections
  • Corroded terminals or connectors
  • Faulty sensors or actuators
  • Communication network issues (e.g., CAN bus problems)
  • Incorrectly configured aftermarket accessories

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 or indicate which module is having communication issues

  2. 2. Inspect Wiring and Connectors

    Visual Inspection: Check the wiring and connectors associated with the modules in question. Look for signs of damage, corrosion, or loose connections

  3. 3. Repair or Replace

    Repair any damaged wires or connectors and ensure all connections are secure

  4. 4. Check Module Power and Ground

    Ensure that the affected module(s) are receiving proper power and ground. Use a multimeter to check voltage and ground continuity

  5. 5. Test Communication Lines

    Use a scan tool to check the communication lines (CAN bus, LIN bus, etc.) for continuity and proper voltage levels. Look for shorts or open circuits

  6. 6. Inspect for Water Intrusion

    Check for signs of water intrusion in the module connectors or wiring harnesses, as moisture can cause communication failures

  7. 7. Reset the Modules

    Clear the trouble codes using the OBD-II scanner and see if the code returns. Sometimes, a temporary glitch can cause communication issues

  8. 8. Check for Software Updates

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

  9. 9. Test Individual Modules

    If you suspect a specific module is causing the issue, you may need to test or replace that module. This may involve swapping it with a known good module if possible

  10. 10. Check for Intermittent Issues

    If the problem is intermittent, monitor the vehicle's performance and check for specific conditions that trigger the code

  11. 11. Consult Technical Service Bulletins (TSBs)

    Look for any TSBs related to the U1305 code for your specific vehicle make and model. Manufacturers may have documented common issues and solutions.1

  12. 12. Professional Diagnosis

    If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership with experience in diagnosing module communication issues. By following these steps, you should be able to identify and resolve the underlying cause of the U1305 code