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U1913 CAN Communication Bus - Missing Message

The OBD2 code U1913 indicates a failure in the CAN communication bus, specifically that a required message is missing from the network, which can affect communication between various vehicle modules

Definition

The OBD2 code U1913 indicates a failure in the CAN communication bus, specifically that a required message is missing from the network, which can affect communication between various vehicle modules

Common causes

  • Faulty CAN bus wiring or connectors
  • Malfunctioning CAN bus module
  • Defective ECU (Electronic Control Unit)
  • Poor ground connections
  • Interference from other electrical components
  • Software issues or bugs in the ECU
  • Damaged or corroded terminals
  • Low battery voltage
  • Faulty sensors communicating over the CAN bus
  • Open or short circuits in the CAN bus network

Common misdiagnoses

  • Faulty CAN bus wiring
  • Defective ECU (Electronic Control Unit)
  • Bad ground connections
  • Malfunctioning sensors
  • Corrupted software or firmware
  • Faulty connectors or terminals
  • Issues with other communication protocols
  • Battery or power supply problems
  • Interference from aftermarket devices
  • Incorrectly configured or incompatible components

Troubleshooting steps

  1. 1. Check for Other Codes

    Use an OBD-II scanner to check for any additional trouble codes. Other codes may provide context or indicate related issues

  2. 2. Inspect the Wiring and Connectors

    Visual Inspection: Look for damaged, frayed, or corroded wiring and connectors related to the CAN bus system

  3. 3. Connector Integrity

    Ensure that all connectors are securely attached and free of corrosion

  4. 4. Test the CAN Bus

    Multimeter Testing: Use a multimeter to check the voltage levels on the CAN High (CAN H) and CAN Low (CAN L) wires. The typical voltage levels should be around 2.5V when idle

  5. 5. Scope Testing

    If available, use an oscilloscope to analyze the CAN signals for proper waveform and communication

  6. 6. Check for Short Circuits or Open Circuits

    Inspect the CAN bus wiring for any short circuits to ground or power, as well as open circuits that could disrupt communication

  7. 7. Inspect Modules on the CAN Bus

    Identify all modules connected to the CAN bus and check for any that may be malfunctioning. A faulty module can disrupt communication

  8. 8. Disconnect modules one at a time to see if the code clears or communication is restored

  9. 9. Check for Software Issues

    Ensure that the vehicle’s software is up to date. Sometimes, a software update can resolve communication issues

  10. 10. If applicable, perform a reset of the vehicle’s control modules

  11. 11. Battery and Ground Connections

    Check the vehicle’s battery voltage and ensure that it is within the normal range

  12. 12. Inspect ground connections for corrosion or looseness, as poor grounding can affect communication

  13. 13. Scan Tool Communication

    Use a professional scan tool to communicate with the vehicle’s modules. If some modules are unresponsive, it may indicate a problem with the CAN bus

  14. 14. Look for Environmental Factors

    Consider if there are any environmental factors (like moisture or extreme temperatures) that could be affecting the CAN bus

  15. 15. Consult Technical Service Bulletins (TSBs)

    Check for any TSBs related to the specific make and model of the vehicle, as manufacturers may have known issues and solutions.1

  16. 16. Professional Diagnosis

    If the issue persists after performing the above steps, consider seeking help from a professional mechanic or automotive technician who has experience with CAN bus systems.Conclusion By following these troubleshooting steps, you can systematically identify and address the underlying cause of the U1913 code. Always ensure safety precautions are taken when working on vehicle electrical systems