U1267 – Communication Bus Off.

The ODBII code U1267 indicates a communication issue where the vehicle’s communication bus is offline or not functioning properly, often due to a fault in the network or a module.

The severity of ODBII code U1267 is moderate to severe.

Common Causes For: U1266 Communication Bus Off.

• Faulty or damaged wiring in the communication bus.
• Failed or malfunctioning control modules.
• Poor connections or corroded terminals in the communication network.
• Short circuits in the communication lines.
• Interference from aftermarket devices or modifications.
• Low battery voltage or power supply issues.
• Faulty or damaged connectors.

Common misdiagnosis for U1267 Communication Bus Off.

• Faulty ECM (Engine Control Module)
• Bad wiring or connectors
• Defective sensors
• Malfunctioning ABS module
• Issues with the body control module (BCM)
• Powertrain control module (PCM) failure
• Battery or charging system problems
• Faulty communication lines or networks
• Incorrectly installed aftermarket accessories
• Software or firmware issues in control modules

Common Troubleshooting Steps

The OBD-II code U1267 indicates a “Communication Bus Off” issue, which typically means that there is a problem with the communication between the vehicle’s control modules. 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 U1267 code:

• Check for Additional Codes: Use an OBD-II scanner to check for any other trouble codes that may be present. Addressing related codes can help pinpoint the issue.
• Inspect Wiring and Connectors: Visually inspect the wiring and connectors associated with the communication bus (CAN bus). Look for signs of damage, corrosion, or loose connections.
• Pay special attention to the connectors at the control modules and any junction points.
• Check for Short Circuits or Open Circuits: Use a multimeter to check for continuity in the communication lines. Look for any short circuits or open circuits that could disrupt communication.
• Test the resistance of the communication wires to ensure they are within specifications.
• Inspect Control Modules: Check the control modules (ECM, BCM, TCM, etc.) for any signs of damage or failure. If a module is malfunctioning, it may not communicate properly with the bus.
• If possible, perform a software update or reset the modules to see if that resolves the issue.
• Test the Communication Bus: Use a scan tool capable of monitoring the communication bus to see if data is being transmitted between modules.
• Check for proper voltage levels on the communication lines (typically around 2.5V to 3.5V for CAN bus).
• Check for Interference: Look for any aftermarket devices or modifications that may interfere with the communication bus, such as alarms, stereo systems, or other electronic devices.
• Perform a Battery Reset: Disconnect the vehicle’s battery for a few minutes to reset the control modules. Reconnect and see if the code reappears.
• Consult Technical Service Bulletins (TSBs): Check for any TSBs related to the U1267 code for your specific vehicle make and model. Manufacturers may have specific fixes or recommendations.
• Replace Faulty Components: If a specific module is identified as faulty, consider replacing it. Ensure that any replacement modules are properly programmed and calibrated.
• Seek Professional Help: If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or technician with experience in automotive electronics and diagnostics. By following these troubleshooting steps, you should be able to identify and resolve the underlying issue causing the U1267 code.