U2340 – Module Communication Failure

The ODBII code U2340 indicates a “Module Communication Failure,” meaning there is a problem with communication between vehicle control modules, which can affect their ability to share data and function properly.

The severity of ODBII code U2340 is generally considered moderate.

Common Causes For: U2339 Control Module Communication Bus Off.

• Faulty wiring or connectors
• Failed control module
• Corrupted software or firmware
• Poor ground connections
• Interference from other electronic devices
• Low battery voltage
• Damaged or corroded pins in connectors
• Communication network issues (e.g., CAN bus problems)

Common misdiagnosis for U2340 U2340: “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 unrelated module failures

Common Troubleshooting Steps

The OBD-II code U2340 indicates a “Module Communication Failure,” which typically means that there is a problem with communication between various control modules in the vehicle. 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 additional trouble codes. Sometimes, other codes can provide context or lead you to the root cause of the communication failure.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the affected modules. 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 modules are receiving the proper voltage. Use a multimeter to check the power supply to the modules.
• Test the Modules: If possible, test the affected modules individually to ensure they are functioning correctly. This may involve using specialized diagnostic tools or swapping with known good modules.
• Check for Interference: Look for any aftermarket devices or modifications that may interfere with the communication between modules. This includes things like alarm systems, stereo systems, or other electronic devices.
• Inspect the CAN Bus: If your vehicle uses a Controller Area Network (CAN) bus for communication, check the integrity of the bus. Look for shorts, opens, or other issues in the wiring.
• Perform a Network Test: Some advanced scan tools can perform a network test to check the communication between modules. This can help identify which module is not communicating properly.
• 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.
• Clear Codes and Test Drive: After performing any repairs or adjustments, clear the trouble codes and take the vehicle for a test drive to see if the code reappears.
• Consult Service Manual: Refer to the vehicle’s service manual for specific diagnostic procedures related to the U2340 code and the modules involved. 1
• Seek Professional Help: If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who has experience with the specific make and model of your vehicle. By following these steps, you can systematically diagnose and potentially resolve the U2340 code and the underlying communication issues in your vehicle.