U1698 – CAN Bus Communication Failure

The ODBII 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.

The severity of ODBII code U1698 is moderate to high.

Common Causes For: U1697 U1697: “Module Communication Failure”

• 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 misdiagnosis for U1698 U1698: “CAN Bus Communication Failure”

• 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)

Common Troubleshooting Steps

When dealing with OBD-II code U1698, which indicates a “CAN Bus Communication Failure,” there are several common troubleshooting steps you can take to diagnose and potentially resolve the issue. Here’s a structured approach:

• 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.
• 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.
• **Wiring Continuity: Use a multimeter to check for continuity in the CAN bus wires. Look for breaks or shorts in the wiring.
• 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.
• 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.
• Disconnect each module one at a time to see if the code clears or communication is restored.
• 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.
• The CAN High and CAN Low lines should show a differential voltage when the bus is active.
• 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.
• Inspect for Interference: Look for sources of electrical interference that may be affecting the CAN bus communication. This can include aftermarket accessories or modifications.
• 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.
• 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.
• 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
• 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.