U002E High Speed CAN Communication Bus Off

Definition

Common causes

• Faulty CAN bus wiring or connectors
• Defective CAN bus module
• Short circuit in the CAN bus
• Open circuit in the CAN bus
• Interference from other electrical components
• Faulty or damaged sensors on the CAN bus
• Software or firmware issues in the control modules
• Low battery voltage or poor power supply to modules
• Grounding issues in the vehicle's electrical system
• Corroded or loose connections in the CAN network

Common misdiagnoses

• Faulty Engine Control Module (ECM)
• Defective Body Control Module (BCM)
• Bad wiring or connectors
• Faulty CAN bus transceiver
• Power supply issues
• Incorrectly configured or programmed modules
• Faulty sensors or actuators on the CAN bus
• Grounding issues
• Intermittent electrical connections
• Software glitches or updates needed

Troubleshooting steps

1. 1. Check for Additional Codes

   Use an OBD-II scanner to check for any other related trouble codes. This can provide more context about the issue

2. 2. Inspect Wiring and Connectors

   Visual Inspection: Look for damaged, frayed, or corroded wiring and connectors related to the CAN bus. Pay special attention to the wiring harnesses that connect various modules

3. 3. Connector Integrity

   Ensure that all connectors are securely attached and free of corrosion

4. 4. Test the CAN Bus

   Multimeter Testing: 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

5. 5. Scope Testing

   If available, use an oscilloscope to analyze the CAN signals. Look for proper waveform patterns and check for noise or interruptions

6. 6. Check for Short Circuits

   Inspect the CAN bus wiring for any short circuits to ground or to other wires. This can cause communication failures

7. 7. Inspect Modules

   Module Functionality: Check the functionality of the modules connected to the CAN bus. A malfunctioning module can disrupt communication

8. 8. Reprogram or Reset Modules

   If a specific module is suspected, try reprogramming or resetting it to see if that resolves the issue

9. 9. 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

10. 10. 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

11. 11. Scan Tool Communication

    Use a professional scan tool to communicate with the vehicle's modules. If some modules are not responding, it may indicate a problem with the CAN bus

12. 12. Replace Faulty Components

    If a specific module or wiring issue is identified, replace the faulty component. After replacement, clear the codes and test drive the vehicle to see if the code returns

13. 13. Consult Technical Service Bulletins (TSBs)

    Check for any manufacturer-specific TSBs related to the U002E code or CAN bus issues for your vehicle make and model.1

14. 14. Professional Diagnosis

    If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership with experience in diagnosing CAN bus issues. By following these steps, you should be able to identify and resolve the underlying cause of the U002E code. Always remember to take safety precautions when working on a vehicle's electrical system