U1255 – Manufacturer Specific Communication Bus Fault.

The ODBII code U1255 indicates a fault in the manufacturer-specific communication bus, suggesting a problem with data transmission between modules in the vehicle’s network.

The severity of ODBII code U1255 is generally considered moderate.

Common Causes For: U1254 U1254: “Module Communication Failure”

• Faulty wiring or connectors in the communication bus.
• Malfunctioning control modules.
• Poor ground connections.
• Corroded or damaged terminals.
• Interference from aftermarket devices.
• Software issues or bugs in the control modules.
• Low battery voltage or power supply issues.

Common misdiagnosis for U1255 Manufacturer Specific Communication Bus Fault.

• Faulty Engine Control Module (ECM)
• Bad wiring or connectors
• Faulty Body Control Module (BCM)
• Incorrectly installed aftermarket accessories
• Faulty communication network components
• Low battery voltage or poor battery connections
• Faulty sensors or actuators
• Software issues or outdated firmware
• Grounding issues
• Intermittent faults in the communication bus

Common Troubleshooting Steps

The OBD-II code U1255 indicates a “Manufacturer Specific Communication Bus Fault.” This code typically points to a problem with the communication between various modules in the vehicle’s network. 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, U1255 may be accompanied by other codes that can provide more context about the issue.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the communication bus (CAN bus, LIN bus, etc.). Look for signs of damage, corrosion, or loose connections.
• Pay special attention to the connectors of the modules that are part of the communication network.
• Check for Short Circuits:
• Use a multimeter to check for short circuits in the communication lines. Ensure that the wires are not shorted to ground or to each other.
• Test the Modules:
• If you suspect a specific module is causing the issue, you can test it by disconnecting it and checking if the code persists. If the code goes away, the module may be faulty.
• Reconnect the module and check for proper operation.
• Inspect the Communication Bus:
• Use a scan tool that can monitor the communication bus. Check for any irregularities in the data being transmitted between modules.
• Look for any modules that are not responding or are showing unusual behavior.
• Check Power and Ground:
• Ensure that all modules on the communication bus have proper power and ground connections. A lack of power or a poor ground can cause communication issues.
• Update Software/Firmware:
• Check if there are any software or firmware updates available for the vehicle’s modules. Sometimes, manufacturers release updates to fix communication issues.
• 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 Manufacturer Documentation:
• Refer to the vehicle’s service manual or manufacturer-specific documentation for any additional troubleshooting steps or specific tests related to the U1255 code.
• 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 make and model of your vehicle. By following these steps, you should be able to identify and resolve the underlying issue causing the U1255 code.