U1393 – Control Module Communication Failure

The ODBII code U1393 indicates a “Control Module Communication Failure,” meaning there is a problem with communication between the vehicle’s control modules, which can affect various systems and functions.

The severity of ODBII code U1393 is moderate to severe.

Common Causes For: U1392 U1392: “Control Module Communication Failure”

• Faulty control module
• Damaged wiring or connectors
• Poor ground connections
• Corroded terminals
• Software issues or bugs
• Communication network issues (e.g., CAN bus problems)
• Low battery voltage or power supply issues
• Interference from aftermarket devices or modifications

Common misdiagnosis for U1393 U1393: “Control Module Communication Failure”

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

Common Troubleshooting Steps

The OBD-II code U1393 indicates a “Control Module Communication Failure.” This code typically suggests that there is a problem with communication between the vehicle’s control modules. 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 control modules. Look for signs of damage, corrosion, or loose connections.
• Pay special attention to the wiring harnesses that connect the modules, as these can be prone to wear and tear.
• Check Power and Ground:
• Ensure that the control modules are receiving proper power and ground. Use a multimeter to check voltage and ground continuity at the module connectors.
• If there is no power or ground, trace the wiring back to the source to identify any breaks or shorts.
• Test Control Modules:
• If possible, test the affected control module(s) to ensure they are functioning correctly. This may involve using specialized diagnostic tools or swapping with a known good module.
• Some modules may have self-diagnostic capabilities that can provide additional information.
• Inspect the CAN Bus:
• U1393 is often related to issues with the Controller Area Network (CAN) bus. Check the CAN bus wiring for shorts, opens, or interference.
• Use an oscilloscope or CAN bus diagnostic tool to monitor the communication signals on the bus.
• Check for Software Updates:
• Sometimes, control modules may require software updates to resolve communication issues. Check with the manufacturer for any available updates.
• Clear Codes and Test Drive:
• After performing the above checks 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.
• Consult Service Manual:
• Refer to the vehicle’s service manual for specific diagnostic procedures related to the U1393 code. This may provide additional insights or steps tailored to your vehicle’s make and model.
• Seek Professional Help:
• If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or technician who has experience with your vehicle’s specific systems. By following these troubleshooting steps, you can systematically identify and resolve the underlying cause of the U1393 code.