U2374 – Control Module Communication Bus Off.

The ODBII code U2374 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 U2374 is moderate to severe.

Common Causes For: U2373 Control Module Communication Bus Off.

• 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 U2374 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 components

Common Troubleshooting Steps

The OBD-II code U2374 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 related issues.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the control modules on the communication bus. 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 control modules have the proper power supply. Use a multimeter to check voltage at the module connectors. If the voltage is low or absent, trace the power supply back to the source.
• Test the Communication Bus:
• Use a scan tool to monitor the communication on the bus. Check if other modules are communicating properly.
• If possible, use an oscilloscope to analyze the data signals on the communication lines (CAN, LIN, etc.) to ensure they are functioning correctly.
• Disconnect Modules: If multiple modules are connected to the same communication bus, try disconnecting them one at a time to isolate the faulty module. Reconnect each module and check for the return of the U2374 code.
• Check for Short Circuits: Inspect the communication lines for any short circuits to ground or to each other. This can cause communication failures.
• Update Software/Firmware: Sometimes, communication issues can be resolved by updating the software or firmware of the control modules. Check with the manufacturer for any available updates.
• Replace Faulty Module: If a specific module is identified as the source of the problem and all other troubleshooting steps have been exhausted, consider replacing the faulty control module.
• Clear Codes and Test Drive: After performing repairs, clear the codes and take the vehicle for a test drive to see if the U2374 code returns.
• Consult Service Manual: If the issue persists, refer to the vehicle’s service manual for specific troubleshooting procedures related to the communication bus and control modules. If you’re not comfortable performing these steps or if the issue remains unresolved, it may be best to consult a professional mechanic or technician for further diagnosis and repair.