U2291 – Control Module Communication Bus Fault

The ODBII code U2291: Control Module Communication Bus Fault indicates a problem with the communication between control modules in a vehicle, suggesting that one or more modules are not able to communicate properly over the vehicle’s data bus.

The severity of ODBII code U2291 is generally considered moderate to severe, as it indicates a communication issue between control modules that can affect vehicle performance and functionality.

Common Causes For: U2290 Lost Communication with the Steering Angle Sensor.

• 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
• Corroded connectors
• Software issues or bugs in the control module
• Low battery voltage or power supply issues
• Faulty communication bus transceiver

Common misdiagnosis for U2291 U2291: 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 U2291 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 trouble codes that may be present. 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, LIN bus, etc.) and ensure they are intact.
• Test the Control Modules: If possible, test the affected control modules to ensure they are functioning correctly. This may involve using specialized diagnostic tools or software.
• Check for any software updates or reprogramming that may be required for the modules.
• 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 be causing the communication failure.
• 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 accessories.
• Perform a Network Test: If you have access to a professional scan tool, perform a network test to check the communication between modules. This can help identify which module is not communicating properly.
• Clear Codes and Test Drive: After performing any repairs or adjustments, clear the trouble codes and take the vehicle for a test drive to see if the code reappears.
• Consult Technical Service Bulletins (TSBs): Check for any TSBs related to the specific make and model of your vehicle. Manufacturers may have issued guidance on common issues related to communication faults.
• Seek Professional Help: If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or technician who specializes in automotive electronics.Conclusion Troubleshooting a U2291 code can be complex due to the nature of vehicle communication systems. Following these steps systematically can help identify and resolve the underlying issue. Always refer to the vehicle’s service manual for specific information related to the make and model you are working on.