U1864 – CAN Bus Communication Failure

The ODBII code U1864: CAN Bus Communication Failure indicates a problem with the communication between modules on the Controller Area Network (CAN) bus, suggesting that one or more modules are not able to send or receive data properly.

The severity of ODBII code **U1864: CAN Bus Communication Failure** is generally considered moderate to severe.

Common Causes For: U1860: Communication Line Fault Detected

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

Common misdiagnosis for U1864: 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
• Incorrectly configured or incompatible modules
• Physical damage to the CAN Bus network

Common Troubleshooting Steps

The OBD-II code **U1864: CAN Bus Communication Failure** indicates a problem with the Controller Area Network (CAN) bus communication in a vehicle. This code typically suggests that there is a communication issue between the various control modules in the vehicle. Here are some common troubleshooting steps to diagnose and resolve this issue:

• Check for Other Codes: Use an OBD-II scanner to check for any additional trouble codes. Other codes may provide more context about the issue.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the CAN bus. Look for signs of damage, corrosion, or loose connections.
• Pay special attention to the connectors on the Engine Control Module (ECM), Transmission Control Module (TCM), and any other modules that communicate over the CAN bus.
• Test the CAN Bus Voltage:
• 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 the bus is idle.
• If the voltage levels are outside the normal range, there may be a short circuit or an open circuit in the wiring.
• Check for Short Circuits:
• Inspect the CAN bus wiring for any short circuits to ground or to each other. This can cause communication failures.
• Test Individual Modules:
• Disconnect each module on the CAN bus one at a time and check if the code clears. This can help identify if a specific module is causing the communication failure.
• Check for Interference:
• Ensure that there are no aftermarket devices or modifications that could be interfering with the CAN bus communication.
• Inspect the Ground Connections:
• Check the ground connections for the control modules. Poor grounding can lead to communication issues.
• Scan for Module Communication:
• Use a scan tool to check if you can communicate with all the modules on the CAN bus. If some modules are unresponsive, it may indicate a problem with those specific modules.
• Check for Software Updates:
• Sometimes, a software update for the vehicle’s control modules can resolve communication issues. Check with the manufacturer for any available updates.
• Replace Faulty Components:
• If a specific module is identified as faulty, it may need to be replaced. Ensure that the replacement module is compatible with the vehicle. 1
• Consult Technical Service Bulletins (TSBs):
• Check for any TSBs related to the U1864 code for your specific vehicle make and model. Manufacturers may have specific recommendations for addressing this issue. 1
• Professional Diagnosis:
• If the issue persists after performing these steps, consider seeking help from a professional mechanic or dealership with experience in diagnosing CAN bus communication issues. By following these troubleshooting steps, you can systematically identify and resolve the underlying cause of the U1864 code.