U2745 – Vehicle Communication Bus Malfunction

The ODBII code U2745 indicates a malfunction in the vehicle communication bus, which affects the communication between various control modules in the vehicle.

The severity of ODBII code U2745 is generally considered moderate to severe.

Common Causes For: U2744 Invalid Data Received from Vehicle Control Module.

• Faulty wiring or connectors in the communication bus
• Malfunctioning control modules
• Corrupted software or firmware in control modules
• Poor ground connections
• Short circuits or open circuits in the communication lines
• Interference from aftermarket devices
• Damaged or defective communication bus components
• Low battery voltage or power supply issues

Common misdiagnosis for U2745 Vehicle Communication Bus Malfunction

• Faulty Engine Control Module (ECM)
• Defective Body Control Module (BCM)
• Bad wiring or connectors
• Faulty sensors
• Issues with the powertrain control module (PCM)
• Incorrectly diagnosed transmission problems
• Battery or charging system issues
• Software or firmware glitches in modules
• Faulty diagnostic tools or procedures
• Misinterpretation of other communication codes.

Common Troubleshooting Steps

The OBD-II code U2745 indicates a “Vehicle Communication Bus Malfunction.” This code typically points to issues with the communication between various control modules in the vehicle. 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 problem.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the communication bus (CAN bus). Look for signs of damage, corrosion, or loose connections.
• Pay special attention to the connectors on the control modules, as well as any junction points in the wiring harness.
• Test the Communication Bus:
• Use a multimeter or an oscilloscope to check the voltage levels on the CAN bus wires. The typical voltage levels should be around 2.5V to 3.5V when the vehicle is on.
• Check for short circuits or open circuits in the communication lines.
• Check Control Modules:
• Ensure that all control modules are functioning properly. A malfunctioning module can disrupt communication on the bus.
• If possible, perform a software update or reset on the control modules.
• Inspect Ground Connections:
• Ensure that all ground connections related to the control modules and communication bus are secure and free of corrosion.
• Look for Interference:
• Check for any aftermarket devices or modifications that may interfere with the vehicle’s communication systems, such as alarms, remote starters, or audio systems.
• Perform a Network Test:
• Some advanced scan tools can perform a network test to check the integrity of the communication bus and identify any modules that are not responding.
• Check for Battery Voltage Issues:
• Ensure that the vehicle’s battery is in good condition and that the voltage is within the normal range. Low voltage can cause communication issues.
• Clear Codes and Test Drive:
• After performing the above checks and repairs, clear the trouble codes and take the vehicle for a test drive to see if the code reappears.
• Consult Service Manual:
• Refer to the vehicle’s service manual for specific diagnostic procedures related to the communication bus and any manufacturer-specific troubleshooting steps. 1
• Seek Professional Help:
• If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who has experience with the specific vehicle make and model. By following these steps, you should be able to identify and resolve the underlying issue causing the U2745 code.