WOMS
U code network Medium severity

U2999 is a generic communication error code that indicates a problem with the vehicle's communication network

The OBD2 code U2999 indicates a generic communication error within the vehicle's communication network, suggesting a problem with data transmission between modules

Definition

The OBD2 code U2999 indicates a generic communication error within the vehicle's communication network, suggesting a problem with data transmission between modules

Common causes

  • Faulty wiring or connectors in the communication network
  • Malfunctioning control modules
  • Corrupted software or firmware in a control module
  • Poor ground connections
  • Interference from aftermarket devices
  • Low battery voltage or weak battery
  • Faulty OBD-II port or connectors

Common misdiagnoses

  • Faulty ECM (Engine Control Module)
  • Bad wiring or connectors
  • Defective sensors
  • Incorrectly installed aftermarket accessories
  • Faulty TCM (Transmission Control Module)
  • Issues with the CAN bus system
  • Malfunctioning body control module (BCM)
  • Battery or charging system problems
  • Software or firmware issues
  • Grounding problems

Troubleshooting steps

  1. 1. Check for Other Codes

    Use an OBD-II scanner to check for any additional trouble codes. U2999 may be accompanied by other codes that can provide more context about the issue

  2. 2. Inspect the OBD-II Connector

    Ensure that the OBD-II connector is clean and free of corrosion

  3. 3. Check for any loose or damaged pins in the connector

  4. 4. Examine Wiring and Connectors

    Inspect the wiring harnesses related to the communication network (CAN bus, LIN bus, etc.) for any signs of damage, fraying, or corrosion

  5. 5. Look for any loose or disconnected connectors that may affect communication

  6. 6. Check for Short Circuits or Open Circuits

    Use a multimeter to check for continuity in the communication lines

  7. 7. Look for any short circuits or open circuits that could disrupt communication

  8. 8. Inspect Modules and Components

    Identify and inspect the modules that are part of the communication network (e.g., Engine Control Module (ECM), Transmission Control Module (TCM), Body Control Module (BCM))

  9. 9. Ensure that all modules are functioning properly and are powered on

  10. 10. Test the Communication Network

    Use a scan tool to monitor the communication between modules. Check if all modules are responding correctly

  11. 11. If possible, perform a network test to see if the communication lines are functioning as expected

  12. 12. Check for Software Updates

    Verify if there are any software updates available for the vehicle’s modules. Sometimes, communication issues can be resolved with a software update

  13. 13. Inspect for Environmental Factors

    Check for any environmental factors that may affect communication, such as water intrusion or excessive heat

  14. 14. Clear Codes and Test Drive

    After performing inspections and repairs, clear the trouble codes using the OBD-II scanner

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

  16. 16. 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 known communication issues.1

  17. 17. Seek Professional Help

    If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership with experience in diagnosing communication network issues. By following these steps, you can systematically identify and address the underlying cause of the U2999 code