WOMS
U code network Medium severity

U1121 Lost Communication with Object 1

The OBD2 code U1121 indicates a loss of communication with a specific module or component in the vehicle, referred to as "Object 1," which may affect various systems or functions

Definition

The OBD2 code U1121 indicates a loss of communication with a specific module or component in the vehicle, referred to as "Object 1," which may affect various systems or functions

Common causes

  • Faulty wiring or connectors
  • Failed control module
  • Corroded or damaged connectors
  • Poor ground connection
  • Intermittent electrical issues
  • Software or firmware issues
  • Faulty sensors or actuators
  • Communication network issues (e.g., CAN bus problems)

Common misdiagnoses

  • Faulty wiring or connectors
  • Defective control module
  • Software issues or updates needed
  • Sensor malfunctions
  • Power supply problems
  • Grounding issues
  • Intermittent communication faults
  • Incorrectly configured aftermarket accessories

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. Other codes can provide context and help identify the root cause of the communication issue

  2. 2. Inspect Wiring and Connectors

  3. 3. Visually inspect the wiring and connectors associated with the affected module (Object 1). Look for signs of damage, corrosion, or loose connections

  4. 4. Pay special attention to the CAN bus wiring, as it can be sensitive to damage

  5. 5. Check for Short Circuits or Open Circuits

  6. 6. Use a multimeter to test for continuity in the wiring. Look for any short circuits or open circuits that could be causing communication issues

  7. 7. Verify Power and Ground

  8. 8. Ensure that the affected module has proper power and ground connections. Use a multimeter to check voltage and ground integrity

  9. 9. Inspect the Affected Module

  10. 10. If the wiring and connections are intact, the issue may lie with the module itself. Check for any signs of physical damage or water intrusion

  11. 11. If possible, test the module in another vehicle or replace it with a known good module to see if the problem persists

  12. 12. Check for Interference

  13. 13. Look for any aftermarket devices or modifications that may interfere with the vehicle's communication network. This includes alarms, stereo systems, or other electronic devices

  14. 14. Scan for Communication Issues

  15. 15. Use a professional-grade scan tool to perform a network scan. This can help identify which module is not communicating properly and may provide more detailed information about the communication network

  16. 16. Reset the Codes

  17. 17. After performing 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. Check for any manufacturer-specific TSBs related to U1121 or communication issues. There may be known fixes or recalls that apply to your vehicle

  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 specializes in automotive electronics and diagnostics. By following these steps, you can systematically diagnose and potentially resolve the U1121 code and its underlying communication issues