U1627 – Vehicle Communication Bus Malfunction

The ODBII code U1627 indicates a malfunction in the vehicle communication bus, which affects the ability of various modules to communicate with each other.

The severity of ODBII code U1627 is moderate.

Common Causes For: U1625 U1625: “Vehicle Communication Bus Malfunction”

• Faulty OBD-II connector
• Damaged wiring or connectors in the communication circuit
• Malfunctioning control modules
• Poor ground connections
• Corroded or loose pins in the connectors
• Software issues or bugs in the control modules
• Interference from aftermarket devices
• Faulty or incompatible diagnostic tools
• Low battery voltage or power supply issues
• Faulty communication bus (CAN bus) components

Common misdiagnosis for U1627 U1627: “Vehicle Communication Bus Malfunction”

• Faulty OBDII connector
• Bad ground connections
• Defective ECM (Engine Control Module)
• Faulty wiring or harness issues
• Malfunctioning sensors
• Issues with the CAN bus system
• Problems with other control modules
• Battery or power supply issues

Common Troubleshooting Steps

The OBD-II code U1627 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 the 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 damaged, corroded, or loose connections.
• Pay special attention to the connectors on the ECM (Engine Control Module), BCM (Body Control Module), and any other modules that may be involved.
• 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 possible, test the individual control modules for proper operation. This may involve using specialized diagnostic tools or software.
• Ensure that all modules are powered and grounded correctly.
• Inspect the CAN Bus:
• Use an oscilloscope or a CAN bus analyzer to check the signal integrity on the CAN bus. Look for any irregularities in the signal that could indicate a fault.
• Check the termination resistors (typically 120 ohms) at both ends of the CAN bus. If they are missing or faulty, it can cause communication issues.
• Check for Interference:
• Ensure that there are no aftermarket devices or modifications that could be interfering with the communication bus. This includes alarms, stereo systems, or other electronic devices.
• Update Software/Firmware:
• Check if there are any software updates available for the vehicle’s control modules. Sometimes, updating the firmware can resolve 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 Technical Service Bulletins (TSBs):
• Look for any TSBs related to the U1627 code for your specific vehicle make and model. Manufacturers may have specific recommendations or known issues that can help in troubleshooting.
• Professional Diagnosis:
• If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership with experience in diagnosing communication issues. By following these steps, you should be able to identify and resolve the underlying cause of the U1627 code.