U1923 – Module Communication Failure

The ODBII code U1923 indicates a “Module Communication Failure,” meaning there is a problem with communication between vehicle modules, often due to a fault in the wiring, connectors, or the modules themselves.

The severity of ODBII code U1923 is moderate.

Common Causes For: U1922 U1922: “Module Communication Failure”

• Faulty wiring or connectors
• Failed or malfunctioning control module
• Corrupted software or firmware in the module
• Poor ground connections
• Interference from aftermarket devices
• Low battery voltage or power supply issues
• Communication network issues (e.g., CAN bus problems)

Common misdiagnosis for U1923 U1923: “Module Communication Failure”

• Faulty wiring or connectors
• Defective control module
• Software issues or updates needed
• Battery or power supply problems
• Grounding issues
• Intermittent communication issues
• Other module failures (e.g., ABS, BCM)
• Corrupted data or configuration errors

Common Troubleshooting Steps

The OBD-II code U1923 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, other codes can provide additional context for the communication failure.
• 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.
• Test the Module: If possible, test the affected module to ensure it is functioning correctly. This may involve using specialized diagnostic tools or swapping the module with a known good one.
• Check for Communication:
• Use a scan tool to check if you can communicate with the affected module. If you cannot, it may indicate a problem with the module itself or the communication network.
• Check the communication lines (CAN bus, LIN bus, etc.) for continuity and proper signal levels.
• Inspect the CAN Bus: If the vehicle uses a CAN bus system, check for issues such as:
• Short circuits or open circuits in the CAN wiring.
• Termination resistors that may be missing or faulty.
• Interference from aftermarket devices or modifications.
• Look for Software Issues: Sometimes, a software glitch can cause communication failures. Check if there are any available software updates for the affected module(s) and apply them if necessary.
• Reset the Modules: Disconnect the battery for a few minutes to reset the modules. Reconnect the battery and see if the code reappears.
• Consult Technical Service Bulletins (TSBs): Check for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance on known issues related to module communication.
• Professional Diagnosis: If the issue persists after performing the above steps, it may be necessary to seek assistance from a professional mechanic or dealership with advanced diagnostic equipment. By following these steps, you can systematically identify and resolve the underlying cause of the U1923 code.