U1742 – Module Communication Failure

The ODBII code U1742 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 U1742 is moderate.

Common Causes For: U1740 U1740: Transmission Control Module Communication Error

• Faulty wiring or connectors
• Failed or malfunctioning control module
• Poor ground connections
• Intermittent electrical issues
• Software or firmware issues
• Corroded terminals
• Communication network issues (e.g., CAN bus problems)
• Low battery voltage or power supply issues

Common misdiagnosis for U1742 U1742: “Module Communication Failure”

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

Common Troubleshooting Steps

The OBD-II code U1742 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 Additional Codes: Use an OBD-II scanner to check for any other trouble codes that may be present. Sometimes, multiple codes can provide more context for the issue.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the affected 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 modules are receiving the proper voltage. Use a multimeter to check the power supply to the modules.
• Verify that the fuses related to the communication network are intact.
• Test the Communication Network:
• Use a scan tool to check the communication between modules. Some scan tools can perform a network test to see if all modules are communicating properly.
• Look for any modules that are not responding or showing errors.
• Inspect the CAN Bus:
• If your vehicle uses a Controller Area Network (CAN) bus, check for issues with the bus itself. Look for shorts, opens, or resistance issues in the wiring.
• You can use an oscilloscope to check the signal integrity on the CAN bus lines.
• Reset the Modules:
• Sometimes, simply resetting the affected 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 vehicle’s control modules. Sometimes, communication issues can be resolved with an update.
• Replace Faulty Modules:
• If a specific module is identified as faulty and not communicating, it may need to be replaced. Ensure that the replacement module is compatible with your vehicle.
• Consult Technical Service Bulletins (TSBs):
• Check for any TSBs related to the U1742 code for your specific vehicle make and model. Manufacturers may have specific recommendations or known issues that can help in troubleshooting.
• Professional Diagnosis:
• If the issue persists after performing the above steps, consider seeking help from a professional mechanic or 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 U1742 code.