U0068: Vehicle Communication Bus E (+) High

Definition

The OBD2 code U0068 indicates a communication issue where the Vehicle Communication Bus E is experiencing a high voltage condition, suggesting a potential fault in the communication network between modules

Common causes

Faulty CAN bus wiring
Short circuit in the CAN bus
Faulty control module
Poor ground connection
Corroded connectors
Intermittent electrical connections
Faulty or damaged sensors
Software issues in the control module

Common misdiagnoses

Faulty Engine Control Module (ECM)
Faulty Transmission Control Module (TCM)
Bad wiring or connectors
Faulty Body Control Module (BCM)
Issues with the CAN bus system
Faulty sensors or actuators
Battery or charging system problems
Faulty diagnostic tools or software issues

Troubleshooting steps

1. Check for Additional Codes

Use an OBD-II scanner to check for any other trouble codes that may be present. This can provide more context about the issue
2. Inspect Wiring and Connectors
3. Visually inspect the wiring and connectors associated with the Vehicle Communication Bus E. Look for signs of damage, corrosion, or loose connections
4. Pay special attention to any connectors that may have been disturbed during repairs or maintenance
5. Check for Short Circuits
6. Use a multimeter to check for short circuits in the wiring. Measure the resistance between the communication lines and ground to ensure there are no unintended connections
7. Test the Modules
8. Identify the modules that communicate over Bus E. Common modules may include the engine control module (ECM), transmission control module (TCM), or other body control modules
9. Check if the modules are functioning properly. If one module is faulty, it can disrupt communication on the bus
10. Inspect the Bus Termination
11. Ensure that the communication bus is properly terminated. A missing or faulty termination resistor can cause communication issues
12. Check for Interference
13. Look for any aftermarket devices or modifications that may interfere with the communication bus. This includes alarm systems, stereo systems, or other electronic devices
14. Perform a Network Test
15. If available, use a scan tool that can perform a network test to check the communication between modules. This can help identify which module is not responding
16. Clear Codes and Test Drive
17. After performing inspections and repairs, clear the trouble codes and take the vehicle for a test drive to see if the code returns
18. Refer to the vehicle's service manual for specific diagnostic procedures related to the communication bus and the modules involved
19. Seek Professional Help
20. If the issue persists after performing these 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 issue causing the U0068 code

Definition

Common causes

Common misdiagnoses

Troubleshooting steps

1. Check for Additional Codes

2. Inspect Wiring and Connectors

3. Visually inspect the wiring and connectors associated with the Vehicle Communication Bus E. Look for signs of damage, corrosion, or loose connections

4. Pay special attention to any connectors that may have been disturbed during repairs or maintenance

5. Check for Short Circuits

6. Use a multimeter to check for short circuits in the wiring. Measure the resistance between the communication lines and ground to ensure there are no unintended connections

7. Test the Modules

8. Identify the modules that communicate over Bus E. Common modules may include the engine control module (ECM), transmission control module (TCM), or other body control modules

9. Check if the modules are functioning properly. If one module is faulty, it can disrupt communication on the bus

10. Inspect the Bus Termination

11. Ensure that the communication bus is properly terminated. A missing or faulty termination resistor can cause communication issues

12. Check for Interference

13. Look for any aftermarket devices or modifications that may interfere with the communication bus. This includes alarm systems, stereo systems, or other electronic devices

14. Perform a Network Test

15. If available, use a scan tool that can perform a network test to check the communication between modules. This can help identify which module is not responding

16. Clear Codes and Test Drive

17. After performing inspections and repairs, clear the trouble codes and take the vehicle for a test drive to see if the code returns

18. Refer to the vehicle's service manual for specific diagnostic procedures related to the communication bus and the modules involved

19. Seek Professional Help

20. If the issue persists after performing these 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 issue causing the U0068 code