U2166 – Module Communication Failure

The ODBII code U2166: Module Communication Failure indicates a problem with communication between the vehicle’s control modules, suggesting that one or more modules are not responding or are unable to communicate properly with each other.

The severity of ODBII code U2166 is moderate.

Common Causes For: U2164 U2164: “Module Communication Failure”

• Faulty wiring or connectors
• Malfunctioning control module
• Poor ground connections
• Corroded or damaged pins
• Communication network issues (e.g., CAN bus problems)
• Software or firmware issues
• Intermittent electrical connections
• Low battery voltage or power supply issues

Common misdiagnosis for U2166 U2166: Module Communication Failure

• Faulty wiring or connectors
• Defective control modules
• Battery or power supply issues
• Software or firmware glitches
• Communication network problems (e.g., CAN bus issues)
• Grounding issues
• Intermittent faults in sensors or actuators

Common Troubleshooting Steps

The OBD-II code U2166 indicates a “Module Communication Failure,” which typically means that there is a problem with communication between the vehicle’s control modules. 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 other trouble codes that may be present. Sometimes, multiple codes can provide more context for the issue.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the affected module(s). Look for signs of damage, corrosion, or loose connections.
• Pay special attention to the ground connections, as poor grounding can lead to communication issues.
• Check Power Supply:
• Ensure that the affected module is receiving the proper voltage. Use a multimeter to check the power supply to the module.
• Verify that the fuses related to the module are intact and functioning.
• Test the Module:
• If possible, test the affected module by swapping it with a known good module (if applicable) to see if the problem persists.
• Some modules may have self-diagnostic capabilities; check for any internal fault codes.
• Inspect the CAN Bus:
• If the vehicle uses a Controller Area Network (CAN) bus for communication, check the integrity of the CAN bus wiring.
• Use an oscilloscope or a CAN bus diagnostic tool to monitor the bus for proper signal levels and communication.
• Check for Interference:
• Look for any aftermarket devices or modifications that may interfere with the vehicle’s communication network.
• Disconnect any non-factory accessories to see if the issue resolves.
• Update Software/Firmware:
• Check if there are any software or firmware updates available for the vehicle’s modules. Sometimes, communication issues can be resolved with an update.
• Perform a Hard Reset:
• Disconnect the vehicle’s battery for a few minutes to reset the modules. Reconnect and see if the code reappears.
• Consult Technical Service Bulletins (TSBs):
• Look for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance on known communication issues.
• Professional Diagnosis:
• If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership with advanced diagnostic tools. By following these steps, you should be able to identify the root cause of the U2166 code and take appropriate action to resolve the communication failure.