U2205 – Communication Line Fault Between Modules

The ODBII code U2205 indicates a communication line fault between vehicle modules, suggesting a problem with the data exchange between electronic control units (ECUs).

The severity of ODBII code **U2205** is generally considered moderate to high.

Common Causes For: U2171: Communication Link Failure Between Modules

• Faulty wiring or connectors
• Short circuits in the communication line
• Open circuits in the communication line
• Malfunctioning control modules
• Corroded or damaged connectors
• Interference from aftermarket devices
• Poor ground connections
• Software issues or bugs in modules
• Low battery voltage or power supply issues
• Faulty CAN bus or LIN bus transceiver

Common misdiagnosis for U2205: Communication Line Fault Between Modules

• Faulty wiring or connectors
• Defective control modules
• Low battery voltage
• Corroded terminals
• Intermittent communication issues
• Software glitches or outdated firmware
• Grounding issues
• Faulty sensors or actuators
• Incorrectly configured aftermarket accessories
• Environmental interference (e.g., moisture or debris)

Common Troubleshooting Steps

The OBD-II code **U2205: Communication Line Fault Between Modules** indicates a communication issue between different modules in a vehicle’s network. This can be caused by various factors, including wiring issues, module failures, or interference. 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 related trouble codes. This can provide more context about the issue and help identify which module may be causing the problem.
• Inspect Wiring and Connectors:
• Visually inspect the wiring harnesses and connectors associated with the modules involved in the communication network. Look for signs of damage, corrosion, loose connections, or frayed wires.
• Pay special attention to ground connections, as poor grounding can lead to communication issues.
• Test the Modules:
• If possible, test the modules involved in the communication line. This may involve checking for proper voltage and ground at the module connectors.
• If you have access to a known good module, you can swap it in to see if the problem persists.
• Check for Short Circuits or Open Circuits:
• Use a multimeter to check for continuity in the communication lines (CAN bus, LIN bus, etc.) between the modules. Look for any short circuits or open circuits that could be interrupting communication.
• Inspect the CAN Bus:
• If the vehicle uses a CAN bus system, check the bus for proper voltage levels. The typical voltage levels for a CAN bus are around 2.5V to 3.5V for the CAN High and CAN Low lines.
• Use an oscilloscope if available to analyze the signal waveforms on the CAN bus for any irregularities.
• Check for Interference:
• Look for any aftermarket devices or modifications that may be causing interference with the communication lines. This includes alarms, stereo systems, or other electronic devices.
• Reset the Modules:
• Sometimes, simply resetting the modules by disconnecting the battery for a few minutes can clear temporary communication faults. After reconnecting, check if the code reappears.
• 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.
• Consult Wiring Diagrams:
• Refer to the vehicle’s service manual for wiring diagrams to understand the communication network and identify any specific modules that may be involved in the fault.
• Professional Diagnosis:
• If the issue persists after performing the above steps, it may be necessary to consult a professional technician or dealership for further diagnosis. They may have specialized tools and equipment to pinpoint the issue more accurately. By following these steps, you should be able to identify and resolve the communication line fault indicated by the U2205 code.