U2103 – Lost Communication with Vehicle Control Module.

The ODBII code U2103 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 ODBII code U2103 is generally considered moderate to severe.

Common Causes For: U2102 Lost Communication with Vehicle Control Module.

• Faulty Vehicle Control Module (VCM)
• Damaged wiring or connectors
• Poor ground connections
• Corrupted software or firmware
• Faulty communication network (CAN bus issues)
• Malfunctioning sensors or actuators
• Battery or power supply issues
• Intermittent electrical connections

Common misdiagnosis for U2103 Lost Communication with Vehicle Control Module.

• Faulty Engine Control Module (ECM)
• Bad wiring or connectors
• Faulty Body Control Module (BCM)
• Defective Transmission Control Module (TCM)
• Issues with the power supply or ground connections
• Faulty sensors or actuators
• Software or firmware issues in the control modules
• Corrupted data or communication errors in the CAN bus system

Common Troubleshooting Steps

The OBD-II code U2103 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. Sometimes, other codes can provide context or indicate a related issue.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the vehicle control module (VCM) and any other related modules.
• Look for damaged, corroded, or loose connections that could disrupt communication.
• Check Power and Ground:
• Ensure that the control module has proper power and ground connections. Use a multimeter to check voltage and ground continuity.
• If the module is not receiving power, trace the wiring back to the fuse box and check for blown fuses or damaged wires.
• Test the Control Module:
• If possible, test the control module itself. This may involve using a scan tool to check for communication with the module.
• If the module is unresponsive, it may need to be replaced.
• 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.
• Look for shorts, opens, or interference in the CAN bus lines.
• 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.
• Perform a Hard Reset:
• Disconnect the vehicle’s battery for a few minutes to reset the control modules. Reconnect the battery and see if the code reappears.
• Scan for Communication Issues:
• Use a professional-grade scan tool to perform a network scan. This can help identify which module is not communicating properly.
• Consult Technical Service Bulletins (TSBs):
• Check for any TSBs related to the U2103 code for your specific vehicle make and model. Manufacturers may have specific fixes or recommendations.
• Seek Professional Help:
• If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who specializes in automotive electronics. By following these troubleshooting steps, you can systematically identify and resolve the underlying cause of the U2103 code.