U2191 – Control Module Communication Failure

The ODBII code U2191 indicates a “Control Module Communication Failure,” meaning there is a problem with communication between the vehicle’s control modules, which can affect various systems and functions.

The severity of ODBII code U2191 is moderate.

Common Causes For: U2190 U2190: “Vehicle Communication Bus Malfunction”

• Faulty control module
• Damaged wiring or connectors
• Poor ground connections
• Corroded terminals
• Communication network issues (CAN bus problems)
• Software glitches or outdated firmware
• Intermittent electrical connections
• Battery voltage issues
• Faulty sensors or actuators
• Aftermarket modifications or installations affecting communication

Common misdiagnosis for U2191 U2191: “Control Module Communication Failure”

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

Common Troubleshooting Steps

The OBD-II code U2191 indicates a “Control Module Communication Failure.” This code typically means that there is a problem with communication between the vehicle’s control modules. Here are some common troubleshooting steps to diagnose and resolve this issue:

• Check for Other Codes: Use an OBD-II scanner to check for any additional trouble codes. Sometimes, other codes can provide context or indicate which module is having communication issues.
• Inspect Wiring and Connectors: **Visual Inspection: Check the wiring and connectors associated with the control modules for any signs of damage, corrosion, or loose connections.
• **Repair or Replace: Repair any damaged wires or connectors and ensure that all connections are secure.
• Check Power and Ground: **Power Supply: Verify that the affected control module is receiving the correct voltage. Use a multimeter to check the power supply to the module.
• **Ground Connections: Ensure that the ground connections for the control module are secure and free of corrosion.
• Test Control Modules: **Module Functionality: If possible, test the affected control module to ensure it is functioning correctly. This may involve using specialized diagnostic tools or software.
• **Swap Modules: If you have access to a similar vehicle, you can swap the control module to see if the problem persists.
• Check for Communication Protocol Issues: **CAN Bus Communication: If your vehicle uses a CAN (Controller Area Network) bus, check for issues with the bus itself. Look for short circuits, open circuits, or other faults in the communication lines.
• **Bus Termination: Ensure that the CAN bus is properly terminated. Incorrect termination can lead to communication failures.
• Inspect for Software Issues: **Software Updates: Check if there are any available software updates for the control modules. Sometimes, manufacturers release updates to fix communication issues.
• **Reprogramming: In some cases, reprogramming or resetting the control module may resolve the issue.
• Clear Codes and Test Drive: After performing the above checks and repairs, clear the trouble codes using the OBD-II scanner.
• Take the vehicle for a test drive to see if the code reappears. Monitor the vehicle’s performance and check for any warning lights.
• Consult Technical Service Bulletins (TSBs): Look for any TSBs related to the specific make and model of your vehicle. Manufacturers may have issued bulletins regarding known communication issues and their fixes.
• 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 and diagnostics. By following these troubleshooting steps, you can systematically identify and resolve the underlying cause of the U2191 code.