U1751 – Module Communication Failure

The ODBII code U1751 indicates a “Module Communication Failure,” meaning there is a problem with communication between vehicle control modules, often due to a wiring issue, a faulty module, or a network problem.

The severity of ODBII code U1751 is generally considered moderate to high.

Common Causes For: U1750 U1750: “Module Communication Failure”

• Faulty wiring or connectors
• Failed or malfunctioning module
• Corrupted software or firmware in the module
• Poor ground connections
• Interference from other electronic devices
• Low battery voltage or power supply issues
• Communication network issues (e.g., CAN bus problems)
• Damaged or corroded pins in connectors

Common misdiagnosis for U1751 U1751: “Module Communication Failure”

• Faulty wiring or connectors
• Defective control module
• Software issues or updates needed
• Battery or power supply problems
• Grounding issues
• Intermittent communication issues
• Other communication protocol failures

Common Troubleshooting Steps

The OBD-II code U1751 indicates a “Module Communication Failure,” which typically means that there is a problem with communication between various control modules in the vehicle. 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 point to the root cause of the communication failure.
• Inspect Wiring and Connectors:
• Check the wiring harnesses and connectors associated with the affected modules. Look for signs of damage, corrosion, or loose connections.
• Pay special attention to ground connections, as poor grounding can lead to communication issues.
• Verify Power Supply: Ensure that the affected modules are receiving the proper voltage and ground. Use a multimeter to check the power supply to the modules.
• Check for Module Functionality:
• If possible, test the affected module(s) to ensure they are functioning correctly. This may involve using a scan tool to access the module and check for any internal faults.
• If a module is found to be faulty, it may need to be repaired or replaced.
• Inspect the CAN Bus:
• The Controller Area Network (CAN) bus is responsible for communication between modules. Check for any issues with the CAN bus wiring, such as shorts, opens, or interference.
• Use an oscilloscope or a CAN bus diagnostic tool to monitor the bus signals for proper communication.
• 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 affected modules.
• Reset the Modules: After addressing any identified issues, clear the codes using a scan tool and see if the U1751 code returns. Sometimes, a reset can resolve temporary communication glitches.
• Perform a Network Test: If the issue persists, perform a network test to determine if other modules are communicating properly. This may involve checking the communication lines between modules.
• Consult Technical Service Bulletins (TSBs): Check for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance on known issues related to module communication.
• Seek Professional Help: If you are unable to resolve the issue after performing these steps, it may be necessary to consult a professional mechanic or technician who has experience with automotive electronics and communication systems. By following these troubleshooting steps, you can systematically identify and address the underlying cause of the U1751 code.