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U1698 U1698: "CAN Bus Communication Failure

The OBD2 code U1698 indicates a "CAN Bus Communication Failure," meaning there is a problem with the communication between the vehicle's control modules over the Controller Area Network (CAN) bus

Definition

The OBD2 code U1698 indicates a "CAN Bus Communication Failure," meaning 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 or malfunctioning ECU (Electronic Control Unit)
  • Interference from aftermarket devices
  • Corroded or damaged terminals
  • Poor ground connections
  • Software issues or bugs in the ECU
  • Faulty CAN bus transceiver
  • Low battery voltage or power supply issues

Common misdiagnoses

  • Faulty CAN bus wiring
  • Defective ECU (Electronic Control Unit)
  • Bad ground connections
  • Malfunctioning sensors
  • Corrupted software or firmware
  • Faulty connectors or terminals
  • Interference from aftermarket devices
  • Low battery voltage or power supply issues
  • Issues with other communication protocols (e.g., LIN, K-Line)

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 CAN Bus Wiring

    Visual Inspection: Check the wiring and connectors associated with the CAN bus for any visible damage, corrosion, or loose connections

  3. 3. Wiring Continuity

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

  4. 4. Check the CAN Bus Termination Resistors

    Ensure that the termination resistors (typically 120 ohms) are present and functioning at both ends of the CAN bus. A missing or faulty resistor can cause communication issues

  5. 5. 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

  6. 6. Disconnect each module one at a time to see if the code clears or communication is restored

  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. The CAN High and CAN Low lines should show a differential voltage when the bus is active

  9. 9. Check Power and Ground Connections

    Ensure that all modules on the CAN bus have proper power and ground connections. A poor ground or power supply can lead to communication failures

  10. 10. Inspect for Interference

    Look for sources of electrical interference that may be affecting the CAN bus communication. This can include aftermarket accessories or modifications

  11. 11. Update or Reprogram Modules

    In some cases, a software update or reprogramming of the affected modules may resolve communication issues. Check with the manufacturer for any available updates

  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 TSBs related to the specific make and model of the vehicle. Manufacturers may have known issues and recommended fixes for CAN bus communication problems.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 troubleshooting steps, you can systematically identify and address the underlying cause of the U1698 code