U2390 – Control Module Communication Bus Off.

The ODBII code U2390 indicates a communication issue where a control module is unable to communicate over the vehicle’s communication bus, often due to a fault in the module or wiring.

The severity of ODBII code U2390 is moderate to severe.

Common Causes For: U2389 Invalid Data Received from Vehicle Dynamics Control Module.

• Faulty control module
• Damaged wiring or connectors
• Poor ground connections
• Communication bus short circuit
• Open circuit in the communication bus
• Interference from aftermarket devices
• Software issues or bugs in the control module
• Low battery voltage or power supply issues

Common misdiagnosis for U2390 Control Module Communication Bus Off.

• Faulty control module
• Wiring issues
• Poor ground connections
• Corroded connectors
• Faulty sensors
• Battery or power supply problems
• Software issues or updates needed
• Communication network faults
• Intermittent electrical connections
• Incorrectly installed aftermarket components

Common Troubleshooting Steps

The OBD-II code U2390 indicates a communication issue on the control module communication bus, specifically that a module is “off” or not communicating properly. Here are some common troubleshooting steps to diagnose and resolve this issue:

• Check for Other Codes: Start by scanning the vehicle for any other diagnostic trouble codes (DTCs). Other codes may provide additional context or indicate which module is having communication issues.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the control modules on the communication bus. 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 control module(s) are receiving the proper voltage. Use a multimeter to check the power supply to the module.
• Test the Control Module:
• If you suspect a specific control module is at fault, you can test it by checking for communication using a scan tool.
• If the module is not responding, it may need to be replaced or reprogrammed.
• Inspect the Communication Bus:
• Check the integrity of the communication bus (CAN bus, LIN bus, etc.). Look for short circuits, open circuits, or any other issues that could disrupt communication.
• Use an oscilloscope to monitor the bus signals if you have access to one, as this can help identify communication problems.
• Check for Interference: Sometimes, aftermarket accessories or modifications can interfere with the communication bus. Disconnect any non-factory components and see if the issue persists.
• 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.
• Update Software/Firmware: If the vehicle manufacturer has released updates for the control modules, consider updating the software/firmware, as this can resolve communication issues.
• Consult Technical Service Bulletins (TSBs): Check for any TSBs related to the specific make and model of the vehicle. Manufacturers may have identified common issues and provided solutions.
• Seek Professional Help: If the issue persists after performing these steps, it may be necessary to consult a professional technician or a dealership with specialized diagnostic equipment. By following these steps, you should be able to identify and resolve the underlying issue causing the U2390 code.