WOMS
U code network High severity

U1446 Control Module Communication Bus Off

The OBD2 code U1446 indicates a communication issue where a control module is not able to communicate properly on the vehicle's communication bus, often due to a fault in the module or wiring

Definition

The OBD2 code U1446 indicates a communication issue where a control module is not able to communicate properly 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
  • Short circuit in the communication lines
  • Corroded connectors
  • Software issues or bugs in the control module
  • Low battery voltage or power supply issues
  • Interference from aftermarket devices
  • Faulty sensors or actuators on the bus

Common misdiagnoses

  • Faulty ABS module
  • Defective engine control module (ECM)
  • Malfunctioning transmission control module (TCM)
  • Bad wiring or connectors
  • Faulty body control module (BCM)
  • Incorrectly diagnosed sensor issues
  • Battery or charging system problems
  • Communication issues with other modules
  • Software or firmware issues in control modules
  • Grounding issues in the electrical system

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. This can provide more context about the issue

  2. 2. Inspect Wiring and Connectors

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

  3. 3. Pay special attention to the connectors for the modules involved in the communication bus

  4. 4. Check Power and Ground

    Verify that the affected control module has proper power and ground. Use a multimeter to check voltage at the module's power supply pins and ensure that ground connections are solid

  5. 5. Test the Communication Bus

    Use a scan tool to monitor the communication on the bus. Check for any irregularities in data transmission

  6. 6. If possible, use an oscilloscope to analyze the signal on the communication lines (CAN, LIN, etc.) to ensure they are functioning correctly

  7. 7. Inspect Control Modules

    If a specific module is identified as the source of the problem, consider testing or replacing that module

  8. 8. Ensure that the module is compatible with the vehicle and has the latest firmware or software updates

  9. 9. Check for Short Circuits or Open Circuits

    Use a multimeter to check for short circuits or open circuits in the wiring harness associated with the communication bus

  10. 10. Look for any signs of wear or damage that could cause a break in the circuit

  11. 11. Clear Codes and Test Drive

    After performing any repairs or adjustments, clear the trouble codes using the OBD-II scanner

  12. 12. Take the vehicle for a test drive to see if the code returns

  13. 13. Consult Technical Service Bulletins (TSBs)

    Check for any TSBs related to the U1446 code for your specific vehicle make and model. Manufacturers may have known issues and recommended fixes

  14. 14. Seek Professional Help

    If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership. They may have specialized tools and knowledge to diagnose complex communication issues.Conclusion Troubleshooting OBD-II code U1446 involves a systematic approach to identify and resolve communication issues within the vehicle's control modules. By following these steps, you can often pinpoint the problem and take appropriate action to fix it