U2702 – Control Module Communication Bus Off.

The ODBII code U2702 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 U2702 is moderate to severe.

Common Causes For: U2701 U2701: Control Module Communication Bus Fault

• Faulty control module
• Damaged wiring or connectors
• Poor ground connections
• Communication bus interference
• Software issues or bugs
• Low battery voltage
• Faulty or disconnected sensors
• Corroded terminals or connectors

Common misdiagnosis for U2702 Control Module Communication Bus Off.

• Faulty control module
• Wiring issues
• Poor ground connections
• Corrupted software/firmware
• Faulty sensors
• Battery or power supply problems
• Communication network issues
• Incorrectly installed aftermarket accessories

Common Troubleshooting Steps

The OBD-II code U2702 indicates a communication issue between control modules in a vehicle, specifically that a control module is “bus off.” This typically means that the module has detected a fault in the communication bus and has stopped transmitting messages to prevent further issues. Here are some common troubleshooting steps to diagnose and resolve the U2702 code:

• Check for Additional Codes: Use an OBD-II scanner to check for any other trouble codes that may be present. Other codes can provide context and help identify the root cause of 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 CAN (Controller Area Network) bus wiring, as this is often where communication issues arise.
• Test the Control Module: If possible, test the control module that is reporting the U2702 code. This may involve bench testing or swapping with a known good module to see if the problem persists.
• Check for Short Circuits or Open Circuits: Use a multimeter to check for short circuits or open circuits in the communication lines. This includes checking the CAN high and CAN low lines for continuity and proper voltage levels.
• Inspect for Interference: Look for any aftermarket devices or modifications that may be interfering with the communication bus. This can include alarms, stereo systems, or other electronic devices.
• Check Power and Ground: Ensure that the control module has a proper power supply and ground. Use a multimeter to verify voltage levels at the module’s power and ground pins.
• Clear Codes and Test Drive: After performing inspections 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.
• Update Software/Firmware: In some cases, updating the vehicle’s software or firmware may resolve communication issues. Check with the manufacturer for any available updates.
• 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 communication bus 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. By following these troubleshooting steps, you can systematically identify and resolve the underlying issue causing the U2702 code.