WOMS
U code network Medium severity

U1337 U1337: "Control Module Communication Fault

The OBD2 code U1337 indicates a communication fault between control modules in a vehicle, suggesting that one or more modules are not properly communicating with each other

Definition

The OBD2 code U1337 indicates a communication fault between control modules in a vehicle, suggesting that one or more modules are not properly communicating with each other

Common causes

  • Faulty control module
  • Poor electrical connections
  • Damaged wiring harness
  • Corroded connectors
  • Software issues or bugs
  • Low battery voltage
  • Faulty ground connections
  • Interference from aftermarket devices
  • Communication network issues (CAN bus problems)

Common misdiagnoses

  • Faulty control module
  • Wiring issues
  • Poor ground connections
  • Corrupted software or firmware
  • Faulty sensors
  • Battery or charging system problems
  • Intermittent connection issues
  • Communication network faults (CAN bus issues)

Troubleshooting steps

  1. 1. Check for Other Codes

    Use an OBD-II scanner to check for any additional trouble codes. Sometimes, other codes can provide context or lead to the root cause of the communication fault

  2. 2. Inspect Wiring and Connectors

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

  3. 3. Pay special attention to the wiring harnesses that connect the affected modules

  4. 4. Check Power and Ground

    Ensure that the control modules have proper power and ground connections. Use a multimeter to check voltage and ground continuity

  5. 5. Verify that fuses related to the control modules are intact

  6. 6. Test Control Modules

    If possible, test the affected control modules individually to ensure they are functioning correctly. This may involve using specialized diagnostic tools or software

  7. 7. If a specific module is identified as faulty, consider replacing it

  8. 8. Check for Intermittent Issues

    Sometimes, communication faults can be intermittent. Monitor the vehicle for any patterns or specific conditions under which the fault occurs (e.g., temperature, driving conditions)

  9. 9. Update Software/Firmware

    Check if there are any software or firmware updates available for the control modules. Manufacturers may release updates to fix known communication issues

  10. 10. Clear Codes and Test Drive

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

  11. 11. Consult Technical Service Bulletins (TSBs)

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

  12. 12. Professional Diagnosis

    If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership. They may have access to advanced diagnostic tools and resources

  13. 13. Check for Environmental Factors

    Sometimes, environmental factors such as moisture or extreme temperatures can affect module communication. Ensure that the vehicle is in a suitable environment for testing. By following these troubleshooting steps, you can systematically identify and resolve the underlying cause of the U1337 code