U2807 – Control Module Communication Bus Off.

The ODBII code U2807 indicates a communication issue where a control module is not able to communicate properly on the vehicle’s communication bus, often due to a fault in the module or wiring.

The severity of ODBII code U2807 is moderate to high.

Common Causes For: U2805 U2805: Control Module Communication Bus Fault

• Faulty control module
• Poor electrical connections or wiring issues
• Short circuits in the communication lines
• Corroded connectors
• Faulty or damaged communication bus (CAN bus)
• Software or firmware issues in the control module
• Power supply problems to the control module
• Interference from aftermarket devices or modifications

Common misdiagnosis for U2807 Control Module Communication Bus Off.

• Faulty control module
• Wiring issues
• Poor ground connections
• Corrupted software/firmware
• Faulty sensors
• Battery or power supply problems
• Communication network issues
• Intermittent connection problems

Common Troubleshooting Steps

The OBD-II code U2807 indicates a communication issue on the control module communication bus, specifically that a control module is “off” or not communicating properly. 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 U2807 code:

• Check for Additional Codes: Use an OBD-II scanner to check for any other trouble codes that may be present. This can provide additional context for the issue.
• Inspect Wiring and Connectors: Visually inspect the wiring and connectors related to 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 the Control Modules: Identify the control modules on the communication bus and check if they are functioning properly. This may involve checking for power and ground at the module connectors.
• If possible, test the modules individually to see if they are communicating correctly.
• Test the Communication Bus: Use a multimeter or an oscilloscope to check the communication signals on the bus. Look for proper voltage levels and signal integrity.
• If you have access to a scan tool that can monitor live data, check if the modules are responding to requests.
• Inspect for Short Circuits or Open Circuits: Check for any short circuits or open circuits in the communication lines. This may involve using a multimeter to test continuity and resistance in the wiring.
• Check for Interference: Ensure that there are no aftermarket devices or modifications that could be interfering with the communication bus. This includes things like alarm systems, stereo installations, or other electronic devices.
• Reset the Codes: After performing inspections and repairs, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns.
• 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 common issues related to communication bus problems.
• Replace Faulty Components: If a specific control module is identified as faulty, it may need to be replaced. Ensure that any replacement modules are properly programmed and configured for the vehicle.
• 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 automotive electronics and communication systems. By following these troubleshooting steps, you can systematically identify and resolve the underlying issue causing the U2807 code.