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U code network Medium severity

U1395 U1395: "Control Module Communication Failure

The OBD2 code U1395 indicates a "Control Module Communication Failure," meaning there is a problem with communication between the vehicle's control modules, which can affect various systems and functions

Definition

The OBD2 code U1395 indicates a "Control Module Communication Failure," meaning there is a problem with communication between the vehicle's control modules, which can affect various systems and functions

Common causes

  • Faulty wiring or connectors
  • Failed control module
  • Poor ground connections
  • Corroded or damaged connectors
  • Software issues or bugs
  • Intermittent electrical issues
  • Communication network faults (e.g., CAN bus issues)
  • Low battery voltage or power supply issues
  • Aftermarket modifications or installations affecting communication
  • Faulty sensors or actuators affecting communication pathways

Common misdiagnoses

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

Troubleshooting steps

  1. 1. Check for Additional Codes

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

  2. 2. Inspect Wiring and Connectors

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

  4. 4. Pay special attention to the wiring harnesses that connect the modules, as these can be prone to wear and tear

  5. 5. Check Power and Ground

  6. 6. Ensure that the control modules are receiving proper power and ground. Use a multimeter to check voltage and ground continuity at the module connectors

  7. 7. If there is no power or ground, trace the wiring back to the fuse box or battery to identify the issue

  8. 8. Test Control Modules

  9. 9. If possible, test the affected control module(s) to ensure they are functioning correctly. This may involve using specialized diagnostic tools or swapping with a known good module

  10. 10. Some modules may have self-diagnostic capabilities that can provide additional information

  11. 11. Inspect the CAN Bus

  12. 12. The communication between control modules often occurs over a Controller Area Network (CAN) bus. Check for any issues with the CAN bus wiring, such as shorts or opens

  13. 13. Use a CAN bus scanner to monitor the communication and check for any abnormalities

  14. 14. Check for Software Updates

  15. 15. Sometimes, communication issues can be resolved with a software update. Check with the vehicle manufacturer for any available updates for the control modules

  16. 16. Clear Codes and Test Drive

  17. 17. After performing the above checks and repairs, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns

  18. 18. Consult Technical Service Bulletins (TSBs)

  19. 19. 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

  20. 20. Seek Professional Help

  21. 21. If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who has experience with the specific vehicle and its control systems. By following these troubleshooting steps, you can systematically identify and resolve the underlying cause of the U1395 code