U1346 – Control Module Communication Failure

The ODBII code U1346 indicates a communication failure between control modules in a vehicle, suggesting that one or more modules are not properly communicating with each other.

The severity of ODBII code U1346 is moderate to severe.

Common Causes For: U1345 Manufacturer Specific” code, which typically indicates a communication issue between modules in the vehicle’s network.

• Faulty control module
• Poor electrical connections
• Damaged wiring harness
• Corroded connectors
• Software issues or bugs
• Low battery voltage
• Interference from aftermarket devices
• Faulty sensors or actuators
• Grounding issues
• Communication network failure (e.g., CAN bus issues)

Common misdiagnosis for U1346 U1346: Control Module Communication Failure

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

Common Troubleshooting Steps

The OBD-II code U1346 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. Other codes can provide additional 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 ground connections, as poor grounding can lead to communication issues.
• Check for Short Circuits: Use a multimeter to check for short circuits in the wiring harnesses. Ensure that there are no unintended connections between wires.
• Test Control Modules: If possible, test the affected control modules to ensure they are functioning correctly. This may involve using specialized diagnostic tools or swapping with known good modules.
• Inspect the CAN Bus: The Controller Area Network (CAN) bus is responsible for communication between control modules. Check for any issues with the CAN bus wiring, such as breaks or shorts.
• Use an oscilloscope to monitor the CAN bus signals if you have access to one.
• 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 control modules.
• Clear Codes and Test Drive: After performing any repairs or inspections, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns.
• 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 U1346.
• Professional Diagnosis: If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership. They may have access to advanced diagnostic tools and resources.
• Check Battery and Charging System: Ensure that the vehicle’s battery and charging system are functioning properly. Low voltage can cause communication issues between control modules. By following these steps, you should be able to identify and resolve the underlying cause of the U1346 code. Always refer to the vehicle’s service manual for specific diagnostic procedures and specifications.