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U2337 U2337: "CAN Bus Communication Failure

The OBD2 code U2337 indicates a "CAN Bus Communication Failure," which means there is a problem with the communication between the vehicle's control modules over the Controller Area Network (CAN) bus

Definition

The OBD2 code U2337 indicates a "CAN Bus Communication Failure," which means there is a problem with 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 electronic devices
  • Low battery voltage
  • Software issues or bugs in the control module
  • Poor ground connections
  • Damaged or malfunctioning sensors on the CAN network

Common misdiagnoses

  • Faulty Engine Control Module (ECM)
  • Defective Body Control Module (BCM)
  • Bad wiring or connectors
  • Faulty CAN Bus transceiver
  • Malfunctioning sensors
  • Power supply issues
  • Software glitches or updates needed
  • Faulty diagnostic tools or equipment

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 the Wiring and Connectors

    Visual Inspection: Look for any damaged, frayed, or corroded wires in the CAN bus network. Pay special attention to connectors and terminals

  3. 3. Loose Connections

    Ensure that all connectors are securely attached and free of corrosion

  4. 4. Test the CAN Bus Voltage

    Use a multimeter to check the voltage levels on the CAN High and CAN Low wires. The typical voltage should be around 2.5V when the bus is idle

  5. 5. If the voltage is significantly off, it may indicate a problem with the bus or a connected module

  6. 6. Check for Short Circuits

    Inspect the CAN bus wiring for any short circuits to ground or to each other. This can cause communication failures

  7. 7. Examine the Modules on the CAN Bus

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

  8. 8. Check for any signs of failure or malfunction in these modules. A faulty module can disrupt communication

  9. 9. Perform a Network Test

    If you have access to a professional scan tool, perform a network test to see if all modules are communicating properly

  10. 10. Some tools can also provide a "bus off" status, indicating if a module has been disconnected from the network due to a fault

  11. 11. Check for Interference

    Ensure that there are no aftermarket devices or modifications that could be interfering with the CAN bus communication

  12. 12. Clear Codes and Test Drive

    After performing inspections 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 U2337 code. There may be known issues or recalls that could apply to your vehicle

  14. 14. Seek Professional Help

    If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or technician who has experience with CAN bus systems.Additional Notes

  15. 15. Safety First

    Always ensure the vehicle is in a safe state before working on it, especially when dealing with electrical systems

  16. 16. Documentation

    Keep a record of any codes, symptoms, and repairs performed for future reference. By following these steps, you should be able to identify the cause of the U2337 code and take appropriate action to resolve the communication failure