U1670 – CAN Communication Bus – Invalid or Missing Message.

The ODBII code U1670 indicates a problem with the CAN communication bus, specifically that a message is either invalid or missing, which can affect communication between various vehicle modules.

The severity of ODBII code U1670 is moderate to severe.

Common Causes For: U1669 Lost Communication with Body Control Module (BCM)”.

• Faulty CAN bus wiring or connectors
• Defective CAN bus module
• Poor ground connections
• Interference from other electronic devices
• Malfunctioning sensors or actuators
• Software or firmware issues
• Corroded or damaged terminals
• Open or short circuits in the CAN bus
• Low battery voltage or power supply issues
• Faulty or incompatible aftermarket components

Common misdiagnosis for U1670 CAN Communication Bus – Invalid or Missing Message.

• Faulty CAN bus wiring
• Defective ECU (Electronic Control Unit)
• Bad ground connections
• Malfunctioning sensors
• Corrupted software or firmware
• Faulty connectors or terminals
• Interference from aftermarket accessories
• Low battery voltage or power supply issues
• Incorrectly configured or incompatible modules
• Faulty diagnostic tools or equipment

Common Troubleshooting Steps

When dealing with the OBD-II code U1670, which indicates a problem with the CAN (Controller Area Network) communication bus, there are several common troubleshooting steps you can follow to diagnose and potentially resolve the issue. Here’s a structured approach:

• Check for Additional Codes: Use an OBD-II scanner to check for any other trouble codes that may be present. Sometimes, multiple codes can provide more context about the issue.
• Inspect the Wiring and Connectors: **Visual Inspection: Look for any damaged, frayed, or corroded wires and connectors related to the CAN bus. Pay special attention to the connectors at the ECM (Engine Control Module) and other modules on the bus.
• **Secure Connections: Ensure that all connectors are securely plugged in and that there are no loose connections.
• Test the CAN Bus: **CAN Bus Voltage: Use a multimeter to check the voltage levels on the CAN High and CAN Low wires. The typical voltage levels should be around 2.5V when idle and should fluctuate when data is being transmitted.
• **Scope Test: If available, use an oscilloscope to analyze the CAN signals for proper waveform patterns.
• Check for Short Circuits or Open Circuits: Use a multimeter to check for continuity in the CAN bus wiring. Look for any shorts to ground or power, as well as open circuits that could disrupt communication.
• Inspect Modules on the CAN Bus: **Module Functionality: Check if other modules on the CAN bus are functioning properly. If one module is malfunctioning, it can affect the entire network.
• **Disconnect Modules: Temporarily disconnect non-essential modules one at a time to see if the code clears or if communication is restored.
• Check for Interference: Look for any aftermarket devices or modifications that may interfere with the CAN bus communication, such as alarms, stereo systems, or other electronic devices.
• Update or Reprogram Modules: If the vehicle has had recent updates or repairs, ensure that all modules are updated to the latest software version. Sometimes, reprogramming a module can resolve communication issues.
• Inspect the Battery and Ground Connections: Ensure that the vehicle’s battery is in good condition and that all ground connections are clean and secure. Poor grounding can lead to communication issues.
• Perform a Network Test: If you have access to a professional-grade scan tool, perform a network test to check the communication between modules. This can help identify which module is causing the issue.
• Consult Technical Service Bulletins (TSBs): Check for any TSBs related to the U1670 code for your specific vehicle make and model. Manufacturers may have specific fixes or recommendations for this issue.1
• Seek Professional Help: If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who specializes in automotive electronics and CAN bus systems. By following these troubleshooting steps, you should be able to identify the root cause of the U1670 code and take appropriate action to resolve the issue.