U2105 – Lost Communication with Vehicle Control Module.

The ODBII code U2105 indicates a loss of communication with the vehicle control module, suggesting that the module is not responding or is unable to communicate with other modules in the vehicle’s network.

The severity of OBDII code U2105 is generally considered moderate to severe.

Common Causes For: U2104 Lost Communication with Vehicle Control Module.

• Faulty Vehicle Control Module (VCM)
• Damaged wiring or connectors
• Poor ground connections
• Corroded terminals
• Faulty communication network (CAN bus issues)
• Malfunctioning sensors or actuators
• Software or firmware issues
• Battery or power supply problems

Common misdiagnosis for U2105 Lost Communication with Vehicle Control Module.

• Faulty wiring or connectors
• Defective vehicle control module (VCM)
• Malfunctioning engine control module (ECM)
• Issues with the body control module (BCM)
• Problems with the transmission control module (TCM)
• Faulty sensors or actuators
• Battery or charging system issues
• Corrupted software or firmware in control modules
• Grounding issues
• Communication network problems (CAN bus issues)

Common Troubleshooting Steps

The OBD-II code U2105 indicates a “Lost Communication with Vehicle Control Module.” This code typically points to a communication issue between the vehicle’s control modules, which can be caused by various factors. Here are some common troubleshooting steps to diagnose and resolve the issue:

• Check for Other Codes: Use an OBD-II scanner to check for any additional trouble codes. Other codes may provide more context or indicate which module is having communication issues.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors related to the affected control module. 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 control module is receiving the proper voltage. Use a multimeter to check the power supply to the module.
• Verify that the fuses related to the control module are intact and functioning.
• Test the Control Module:
• If possible, test the control module itself. This may involve using specialized diagnostic tools or swapping the module with a known good one to see if the problem persists.
• Inspect the CAN Bus:
• The communication between modules often occurs over the Controller Area Network (CAN) bus. Check for any issues with the CAN bus wiring, such as shorts or opens.
• Use a CAN bus scanner to monitor the communication and identify any anomalies.
• Check for Software Updates:
• Sometimes, communication issues can be resolved with a software update. Check with the manufacturer for any available updates for the control modules.
• Clear Codes and Test Drive:
• After performing any repairs or inspections, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to 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 common issues related to U2105.
• Professional Diagnosis:
• If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership. They may have access to advanced diagnostic tools and resources. By following these steps, you can systematically identify and resolve the underlying cause of the U2105 code.