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U2112 U2112: "CAN Bus Communication Failure

The OBD2 code U2112 indicates a "CAN Bus Communication Failure," meaning there is a disruption or malfunction in the communication between the vehicle's control modules over the Controller Area Network (CAN) bus

Definition

The OBD2 code U2112 indicates a "CAN Bus Communication Failure," meaning there is a disruption or malfunction in the communication between the vehicle's control modules over the Controller Area Network (CAN) bus

Common causes

  • Faulty CAN bus wiring or connectors
  • Short circuit in the CAN bus
  • Open circuit in the CAN bus
  • Faulty control module
  • Corroded or damaged connectors
  • Interference from other electrical components
  • Poor ground connections
  • Software issues or bugs in the control modules
  • Faulty termination resistors
  • Low battery voltage or power supply issues

Common misdiagnoses

  • Faulty CAN Bus wiring
  • Defective ECU (Engine Control Unit)
  • Malfunctioning sensors
  • Bad ground connections
  • Faulty or incompatible aftermarket components
  • Issues with the OBDII connector
  • Software glitches in the vehicle's control modules
  • Battery or power supply issues
  • Corroded connectors or terminals
  • Interference from other electronic devices

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 about the issue

  2. 2. Inspect the CAN Bus Wiring

    Visual Inspection: Check the wiring harnesses and connectors related to the CAN bus for any signs of damage, corrosion, or loose connections

  3. 3. Continuity Test

    Use a multimeter to check for continuity in the CAN bus wires. Look for breaks or shorts in the wiring

  4. 4. Check the Termination Resistors

    The CAN bus requires termination resistors at both ends of the bus. Ensure that these resistors are present and functioning correctly (typically 120 ohms)

  5. 5. Inspect Modules on the CAN Bus

    Identify all modules connected to the CAN bus (e.g., engine control module, transmission control module, ABS module, etc.)

  6. 6. Check for any malfunctioning modules that may be causing communication issues. Disconnecting and reconnecting modules can sometimes reset communication

  7. 7. Test the CAN Bus Signal

    Use an oscilloscope or a CAN bus analyzer to check the signal on the CAN bus. Look for proper voltage levels and signal integrity

  8. 8. A healthy CAN bus should show a square wave signal

  9. 9. Check for Ground Issues

    Ensure that all ground connections related to the CAN bus and the modules are secure and free of corrosion

  10. 10. Inspect for Interference

    Look for any aftermarket devices or modifications that may be interfering with the CAN bus communication (e.g., alarms, stereo systems, etc.)

  11. 11. Perform a Network Scan

    If available, use a professional-grade scan tool to perform a network scan to see which modules are communicating and which are not

  12. 12. Clear Codes and Test Drive

    After performing the above checks and repairs, clear the trouble codes and take the vehicle for a test drive to see if the code returns

  13. 13. Consult Technical Service Bulletins (TSBs)

    Check for any manufacturer-specific TSBs related to the U2112 code or CAN bus issues for your vehicle make and model.1

  14. 14. Seek Professional Help

    If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who specializes in automotive electronics. By following these steps, you should be able to identify and resolve the underlying cause of the U2112 code