U2759 – Control Module Communication Bus Off.

The ODBII code U2759 indicates a communication issue where a control module is unable to communicate on the vehicle’s communication bus, often due to a fault in the module or wiring.

The severity of ODBII code U2759 is typically considered moderate to severe.

Common Causes For: U2757 Control Module Communication Bus Off.

• Faulty control module
• Damaged wiring or connectors
• Poor ground connections
• Communication bus short circuit
• Open circuit in the communication bus
• Corroded connectors
• Software issues or bugs in the control module
• Interference from aftermarket devices
• Low battery voltage or power supply issues
• Faulty or malfunctioning sensors on the bus

Common misdiagnosis for U2759 Control Module Communication Bus Off.

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

Common Troubleshooting Steps

The OBD-II code U2759 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: Start by scanning the vehicle for any other diagnostic trouble codes (DTCs). Other codes may provide additional context or indicate which module is having communication 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 ground connections, as poor grounding can lead to communication issues.
• Check Power Supply:
• Ensure that the affected control module is receiving the proper voltage. Use a multimeter to check the power supply to the module.
• Verify that the fuses related to the control modules are intact and functioning.
• Test the Control Module:
• If possible, test the control module in question. This may involve using a scan tool to check for communication with the module or replacing it with a known good module to see if the issue persists.
• Inspect the Communication Bus:
• Check the CAN (Controller Area Network) bus or other communication lines for shorts, opens, or other faults. Use an oscilloscope or a CAN bus analyzer if available to monitor the bus signals.
• Look for any devices that may be causing interference on the bus.
• Reset the Modules:
• Sometimes, simply resetting the control modules can resolve communication issues. This can be done by disconnecting the battery for a few minutes or using a scan tool to clear the codes.
• Update Software/Firmware:
• Check if there are any software or firmware updates available for the control modules. Sometimes, manufacturers release updates to fix known communication issues.
• Check for Environmental Factors:
• Ensure that there are no environmental factors affecting the communication, such as water intrusion or excessive heat.
• Consult Technical Service Bulletins (TSBs):
• Look for any TSBs related to the specific make and model of the vehicle. Manufacturers may have documented solutions for known issues.
• Professional Diagnosis:
• If the issue persists after performing the above steps, consider seeking help from a professional technician or a dealership. They may have specialized tools and knowledge to diagnose complex communication issues. By following these steps, you should be able to identify and resolve the underlying cause of the U2759 code.