U1548 – Control Module Communication Failure

The ODBII code U1548 indicates a “Control Module Communication Failure,” meaning there is a problem with communication between the vehicle’s control modules, which may affect their ability to share data and function properly.

The severity of ODBII code U1548 is moderate.

Common Causes For: U1546 U1546: “Control Module Communication Failure”

• Faulty control module
• Poor electrical connections
• Damaged wiring harness
• Corroded connectors
• Software issues or bugs
• Low battery voltage
• Interference from aftermarket devices
• Faulty CAN bus communication
• Grounding issues
• Failed or malfunctioning sensors

Common misdiagnosis for U1548 U1548: “Control Module Communication Failure”

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

Common Troubleshooting Steps

The OBD-II code U1548 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 Other Codes: Use an OBD-II scanner to check for any additional trouble codes. Sometimes, other codes can provide context or lead to the root cause of the communication failure.
• 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 affected control modules.
• Check Power and Ground:
• Ensure that the control module in question is receiving proper power and ground. Use a multimeter to check voltage and ground continuity.
• If there is no power or ground, trace the circuit back to find the issue.
• Test the Control Module:
• If the wiring and power supply are good, the control module itself may be faulty. If possible, test the module in another vehicle or replace it with a known good unit to see if the problem persists.
• Inspect the CAN Bus:
• The communication between control modules often occurs over a Controller Area Network (CAN) bus. Check for any issues with the CAN bus wiring, such as shorts or opens.
• Use a CAN bus scanner to monitor the communication and check for any abnormalities.
• Check for Software Updates:
• Sometimes, a software glitch can cause communication issues. Check with the manufacturer for any available software updates for the control modules.
• 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 U1548 code and the control modules involved.
• Professional Diagnosis:
• If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership with experience in diagnosing complex electrical issues. By following these steps, you should be able to identify and resolve the underlying cause of the U1548 code.