U2305 – Control Module Communication Bus Off.

The ODBII code U2305 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 U2305 is moderate to severe.

Common Causes For: U2304 Lost Communication with the Body Control Module (BCM)”.

• Faulty control module
• Damaged wiring or connectors
• Poor ground connections
• Short circuits in the communication bus
• Open circuits 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 U2305 Control Module Communication Bus Off.

• Faulty control module
• Wiring issues
• Poor ground connections
• Corrupted software/firmware
• Faulty sensors
• Battery or power supply issues
• Intermittent connection problems
• Other communication bus errors

Common Troubleshooting Steps

The OBD-II code U2305 indicates a communication issue on the control module communication bus, specifically that a module is “off” or not responding. This can be caused by various factors, including wiring issues, module failures, or problems with the communication bus itself. Here are some common troubleshooting steps to diagnose and resolve the U2305 code:

• Check for Additional Codes: Use an OBD-II scanner to check for any other trouble codes that may be present. This can provide more context about the issue.
• Inspect Wiring and Connectors: Visually inspect the wiring and connectors related to the control modules. Look for signs of damage, corrosion, or loose connections.
• Pay special attention to the communication bus wires (CAN bus) and ensure they are not shorted or open.
• Check Power and Ground: Verify that the affected control module has proper power and ground connections. Use a multimeter to check voltage and ground continuity.
• Test the Control Module: If possible, test the control module that is generating the U2305 code. This may involve swapping it with a known good module or using a diagnostic tool to check its functionality.
• Inspect the Communication Bus: Use an oscilloscope or a CAN bus analyzer to check the communication signals on the bus. Look for any irregularities in the signal patterns.
• Ensure that the termination resistors are present and functioning correctly.
• Check for Intermittent Issues: Sometimes, communication issues can be intermittent. Wiggle the wiring harnesses and connectors while monitoring the communication to see if the issue can be replicated.
• Clear Codes and Test Drive: After performing inspections and repairs, clear the trouble codes and take the vehicle for a test drive to see if the code returns.
• Consult Technical Service Bulletins (TSBs): Check for any manufacturer-specific TSBs related to the U2305 code or communication issues. There may be known fixes or updates available.
• Professional Diagnosis: If the issue persists after performing the above steps, consider seeking help from a professional technician or dealership with advanced diagnostic tools.
• Replace Faulty Components: If a specific faulty module or wiring issue is identified, replace the affected components as necessary. By following these troubleshooting steps, you can systematically identify and resolve the underlying cause of the U2305 code.