U1620 – Data Bus Communication Fault Detected

The ODBII code U1620 indicates a communication fault within the data bus system of a vehicle, suggesting that there is a problem with the transmission of data between modules or components.

The severity of ODBII code U1620 is generally considered moderate.

Common Causes For: U1619 refers to a communication issue between the engine control module (ECM) and the transmission control module (TCM).

• Faulty wiring or connectors in the data bus system.
• 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.
• Faulty or damaged data bus communication lines.

Common misdiagnosis for U1620 U1620: “Data Bus Communication Fault Detected”

• Faulty wiring or connectors
• Defective control modules
• Battery or power supply issues
• Software glitches or updates needed
• Grounding problems
• Intermittent communication issues
• Faulty sensors or actuators
• Corrupted data or configuration errors

Common Troubleshooting Steps

The OBD-II code U1620 indicates a “Data Bus Communication Fault Detected.” This code typically points to issues with the communication between various modules in the vehicle’s network. 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, U1620 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 data bus (CAN bus, LIN bus, etc.) for any signs of damage, corrosion, or loose connections.
• Pay special attention to the connectors on the modules that are part of the communication network.
• Check for Short Circuits or Open Circuits:
• Use a multimeter to check for continuity in the data bus wiring. Look for any short circuits or open circuits that could disrupt communication.
• Check for shorts to ground or power.
• Test Modules:
• Identify the modules that are part of the communication network and test them individually if possible. This may involve checking for proper operation or communication with a scan tool.
• If a specific module is not responding, it may need to be replaced or repaired.
• Inspect the Data Bus:
• Use an oscilloscope or a specialized scan tool to monitor the data bus signals. Look for irregularities in the signal patterns that could indicate a fault.
• Check for proper voltage levels on the data bus lines.
• Check for Software Issues:
• Ensure that all modules have the latest software updates. Sometimes, communication issues can arise from outdated software.
• If a module has been recently replaced, ensure it is properly programmed and configured.
• Clear Codes and Test Drive:
• After performing any repairs or adjustments, 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):
• Check for any manufacturer-specific TSBs related to U1620 or data bus communication issues. There may be known fixes or recalls that apply to your vehicle.
• 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 faults. By following these steps, you should be able to identify and resolve the underlying issue causing the U1620 code.