U2373: Control Module Communication Bus Off

Definition

The OBD2 code U2373 indicates a communication issue where a control module is not able to communicate properly on the vehicle's communication bus, often due to a fault in the module or wiring

Common causes

Faulty control module
Damaged wiring or connectors
Poor ground connections
Communication bus interference
Software issues or bugs
Low battery voltage
Corroded terminals
Faulty or damaged sensors on the bus

Common misdiagnoses

Faulty control module
Wiring issues
Poor ground connections
Corrupted software/firmware
Faulty sensors
Battery or power supply problems
Communication network issues
Intermittent connection problems

Troubleshooting steps

1. Check for Other Codes

Start by scanning the vehicle for any other diagnostic trouble codes (DTCs). Other codes may provide additional context or indicate related issues
2. Inspect Wiring and Connectors
3. Visually inspect the wiring and connectors associated with the control modules on the communication bus. Look for signs of damage, corrosion, or loose connections
4. Pay special attention to the ground connections, as poor grounding can lead to communication issues
5. Check the Control Modules
6. Identify which control module is reporting the U2373 code. This may require consulting the vehicle's service manual or wiring diagrams
7. If possible, test the control module for proper operation. This may involve checking for power and ground at the module, as well as verifying that it is functioning correctly
8. Test the Communication Bus
9. Use a scan tool to monitor the communication on the bus. Check if other modules are communicating properly
10. If you have access to an oscilloscope, you can check the signal integrity on the communication lines (CAN, LIN, etc.) to ensure they are functioning correctly
11. Check for Short Circuits or Open Circuits
12. Use a multimeter to check for short circuits or open circuits in the communication lines. This may involve testing continuity and resistance in the wiring
13. Inspect for Interference
14. Look for any aftermarket devices or modifications that may interfere with the communication bus. This includes alarms, stereo systems, or other electronic devices
15. Update or Reprogram Control Modules
16. In some cases, a software update or reprogramming of the control module may be necessary. Check with the manufacturer for any available updates
17. Clear Codes and Test Drive
18. After performing any repairs or adjustments, clear the codes using a scan tool and take the vehicle for a test drive to see if the code returns
19. Consult Technical Service Bulletins (TSBs)
20. Check for any TSBs related to the U2373 code for your specific vehicle make and model. Manufacturers may have specific recommendations or known issues
21. Seek Professional Help
22. If the issue persists after performing these steps, it may be necessary to consult a professional technician or dealership for further diagnosis. By following these steps, you should be able to identify and resolve the underlying issue causing the U2373 code

Definition

Common causes

Common misdiagnoses

Troubleshooting steps

1. Check for Other Codes

2. Inspect Wiring and Connectors

3. Visually inspect the wiring and connectors associated with the control modules on the communication bus. Look for signs of damage, corrosion, or loose connections

4. Pay special attention to the ground connections, as poor grounding can lead to communication issues

5. Check the Control Modules

6. Identify which control module is reporting the U2373 code. This may require consulting the vehicle's service manual or wiring diagrams

7. If possible, test the control module for proper operation. This may involve checking for power and ground at the module, as well as verifying that it is functioning correctly

8. Test the Communication Bus

9. Use a scan tool to monitor the communication on the bus. Check if other modules are communicating properly

10. If you have access to an oscilloscope, you can check the signal integrity on the communication lines (CAN, LIN, etc.) to ensure they are functioning correctly

11. Check for Short Circuits or Open Circuits

12. Use a multimeter to check for short circuits or open circuits in the communication lines. This may involve testing continuity and resistance in the wiring

13. Inspect for Interference

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

15. Update or Reprogram Control Modules

16. In some cases, a software update or reprogramming of the control module may be necessary. Check with the manufacturer for any available updates

17. Clear Codes and Test Drive

18. After performing any repairs or adjustments, clear the codes using a scan tool and take the vehicle for a test drive to see if the code returns

19. Consult Technical Service Bulletins (TSBs)

20. Check for any TSBs related to the U2373 code for your specific vehicle make and model. Manufacturers may have specific recommendations or known issues

21. Seek Professional Help

22. If the issue persists after performing these steps, it may be necessary to consult a professional technician or dealership for further diagnosis. By following these steps, you should be able to identify and resolve the underlying issue causing the U2373 code