U2711 – Control Module Communication Bus Off.

The ODBII code U2711 indicates a communication issue where a control module is unable to communicate over the vehicle’s communication bus, often due to a fault in the module or wiring.

The severity of ODBII code U2711 is moderate to severe.

Common Causes For: U2710 Control Module Communication Bus Off.

• Faulty control module
• Poor electrical connections
• Damaged wiring or connectors
• Communication bus failure
• Software issues or bugs
• Low battery voltage
• Interference from aftermarket devices
• Faulty sensors or actuators on the bus

Common misdiagnosis for U2711 Control Module Communication Bus Off.

• Faulty control module
• Wiring issues
• Poor ground connections
• Corrupted software/firmware
• Faulty sensors
• Battery or power supply problems
• Intermittent connection issues
• Other communication bus errors

Common Troubleshooting Steps

The OBD-II code U2711 indicates a communication issue on the control module communication bus, specifically that a module is “off” or not communicating properly. 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. Other codes may provide context or indicate which module is having issues.
• 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 connectors for the affected module and any related modules.
• Check Power and Ground:
• Ensure that the affected control module is receiving proper power and ground. Use a multimeter to check voltage at the module’s power and ground pins.
• If there is no power or ground, trace the wiring back to the fuse box or battery to identify the issue.
• Test the Control Module:
• If the wiring and power supply are good, the control module itself may be faulty. If possible, test the module by swapping it with a known good module or using a diagnostic tool to perform a module test.
• Inspect the Communication Bus:
• Check the CAN (Controller Area Network) bus wiring for shorts, opens, or high resistance. Use an oscilloscope or a CAN bus tester to monitor the bus signals.
• Look for any other modules that may be causing interference on the bus.
• Check for Software Updates:
• Sometimes, communication issues can be resolved with a software update. Check with the vehicle manufacturer for any available updates for the control modules.
• Clear Codes and Test Drive:
• After performing the above checks 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):
• Look for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance on common issues related to U2711.
• Professional Diagnosis:
• If the issue persists after performing the above steps, consider seeking help from a professional mechanic or automotive technician who has experience with the specific vehicle and its systems. By following these steps, you should be able to identify and resolve the underlying issue causing the U2711 code.