U2850 – Control Module Communication Bus Fault

The ODBII code U2850: Control Module Communication Bus Fault indicates a communication issue between control modules in a vehicle’s network, suggesting that one or more modules are not able to communicate properly with each other.

The severity of ODBII code U2850 is moderate.

Common Causes For: U2849 U2849: Control Module Communication Bus Off Error

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

Common misdiagnosis for U2850 U2850: Control Module Communication Bus Fault

• Faulty control module
• Wiring issues
• Poor ground connections
• Corrupted software/firmware
• Faulty sensors
• Battery or power supply problems
• Intermittent connection issues
• Other communication bus faults (e.g., CAN bus issues)

Common Troubleshooting Steps

The OBD-II code U2850 indicates a “Control Module Communication Bus Fault.” This code typically points to a problem with the communication between various control modules in the vehicle. Here are some common troubleshooting steps to diagnose and resolve this issue:

• Check for Additional Codes: Use an OBD-II scanner to check for any other related trouble codes. Sometimes, multiple codes can provide more context for the issue.
• Inspect Wiring and Connectors: Visually inspect the wiring and connectors associated with the control modules. Look for signs of damage, corrosion, or loose connections.
• Pay special attention to the communication bus wires (CAN bus) for any signs of wear or damage.
• 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 Control Modules: If possible, test the individual control modules for proper operation. This may involve using specialized diagnostic tools or swapping modules with known good ones.
• Inspect Ground Connections: Ensure that all ground connections for the control modules are secure and free of corrosion. Poor grounding can lead to communication issues.
• Check for Interference: Look for any aftermarket devices or modifications that may interfere with the communication bus. This includes alarms, stereo systems, or other electronic devices.
• Update Software/Firmware: Check if there are any software or firmware updates available for the vehicle’s control modules. Sometimes, manufacturers release updates to fix communication issues.
• Clear Codes and Test Drive: After performing any repairs or adjustments, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns.
• Consult Service Manual: Refer to the vehicle’s service manual for specific diagnostic procedures related to the U2850 code. This may provide additional insights or steps tailored to your vehicle model.
• Seek Professional Help: If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or technician who has experience with your specific vehicle make and model. By following these troubleshooting steps, you can systematically identify and resolve the underlying issue causing the U2850 code.