U2171 – Communication Link Failure Between Modules

The ODBII code U2171: Communication Link Failure Between Modules indicates that there is a problem with the communication network between different electronic control modules in the vehicle, preventing them from exchanging data properly.

The severity of ODBII code **U2171: Communication Link Failure Between Modules** is generally considered moderate to severe.

Common Causes For: U2165: Module Communication Failure

• Faulty wiring or connectors
• Damaged or corroded pins
• Failed control module
• Software issues or bugs
• Poor ground connections
• Intermittent electrical connections
• Low battery voltage
• Faulty communication network (CAN bus)

Common misdiagnosis for U2171: Communication Link Failure Between Modules

• Faulty wiring or connectors
• Defective control modules
• Software issues or programming errors
• Battery or power supply problems
• Grounding issues
• Intermittent communication issues
• Faulty sensors or actuators
• Corrupted data or signal interference

Common Troubleshooting Steps

The OBD-II code **U2171: Communication Link Failure Between Modules** indicates that there is a communication issue between various control modules in the vehicle. This can affect the performance of various systems, including the engine, transmission, and other electronic components. Here are some common troubleshooting steps to diagnose and resolve this issue:

• 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 about the issue.
• Inspect Wiring and Connectors:
• Visually inspect the wiring harnesses and connectors associated with the affected modules. Look for signs of damage, corrosion, or loose connections.
• Pay special attention to ground connections, as poor grounding can lead to communication issues.
• Check for Module Power Supply:
• Ensure that the affected modules are receiving the proper voltage and ground. Use a multimeter to check the power supply to the modules.
• If a module is not powered correctly, it may not communicate with other modules.
• Test Communication Lines:
• Use a scan tool to check the communication lines (CAN bus, LIN bus, etc.) for continuity and proper voltage levels.
• If you have access to an oscilloscope, you can check the signal waveforms on the communication lines to ensure they are functioning correctly.
• Inspect for Short Circuits:
• Check for any short circuits in the wiring that could be causing interference with the communication signals.
• Look for pinched wires or damaged insulation that could lead to shorts.
• Check for Module Malfunction:
• If the wiring and connections are intact, the issue may be with one of the control modules themselves.
• If possible, swap the suspected module with a known good one to see if the problem persists.
• Reset the Modules:
• Sometimes, simply resetting the modules by disconnecting the battery for a few minutes can clear temporary communication issues.
• After reconnecting the battery, check if the code reappears.
• Update Software/Firmware:
• Check if there are any software or firmware updates available for the vehicle’s control modules. Sometimes, communication issues can be resolved with an update.
• Consult Technical Service Bulletins (TSBs):
• Look for any TSBs related to the specific make and model of the vehicle. Manufacturers may have identified common issues and provided solutions.
• Professional Diagnosis:
• If the issue persists after performing the above steps, it may be necessary to seek help from a professional mechanic or dealership with advanced diagnostic tools. By following these steps, you can systematically identify and resolve the communication link failure indicated by the U2171 code.