WOMS
U code network Medium severity

U2021 Invalid /fault data received (Non SCP)

The OBD2 code U2021 indicates that the vehicle's control module has received invalid or faulty data from another module that is not using the SCP (Serial Communication Protocol)

Definition

The OBD2 code U2021 indicates that the vehicle's control module has received invalid or faulty data from another module that is not using the SCP (Serial Communication Protocol)

Common causes

  • Faulty communication between modules
  • Corrupted or damaged wiring harness
  • Poor ground connections
  • Malfunctioning control modules
  • Software issues or bugs in the modules
  • Interference from aftermarket devices
  • Low battery voltage or power supply issues
  • Faulty sensors or actuators
  • Incorrectly configured or programmed modules
  • Environmental factors affecting module performance

Common misdiagnoses

  • Faulty wiring or connectors
  • Malfunctioning control modules
  • Incorrectly programmed modules
  • Communication network issues
  • Sensor failures
  • Software glitches
  • Grounding issues
  • Intermittent electrical faults

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. Addressing other codes may resolve the U2021 code

  2. 2. Inspect Wiring and Connectors

    Examine the wiring and connectors associated with the affected modules. Look for signs of damage, corrosion, or loose connections

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

  4. 4. Check for Module Communication

    Use a scan tool to check if all modules are communicating properly. If some modules are not responding, it may indicate a problem with those specific modules or their connections

  5. 5. Inspect the CAN Bus

    If your vehicle uses a Controller Area Network (CAN) bus, check for issues with the bus itself. Look for shorts, opens, or other faults in the wiring

  6. 6. Use an oscilloscope or a CAN bus analyzer to monitor the bus signals for irregularities

  7. 7. Test the Affected Module

    Identify which module is reporting the U2021 code. If possible, test the module to ensure it is functioning correctly

  8. 8. If the module is faulty, it may need to be repaired or replaced

  9. 9. Check for Software Updates

    Verify if there are any software updates available for the vehicle's modules. Sometimes, manufacturers release updates to fix communication issues

  10. 10. Clear Codes and Test Drive

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

  11. 11. Consult Technical Service Bulletins (TSBs)

    Check for any TSBs related to the U2021 code for your specific vehicle make and model. Manufacturers may have documented known issues and solutions

  12. 12. Professional Diagnosis

    If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership. They may have specialized tools and knowledge to diagnose complex communication issues

  13. 13. Document Findings

    Keep a record of all findings, repairs, and tests performed. This documentation can be helpful for future reference or if further diagnosis is needed. By following these steps, you should be able to identify and resolve the underlying issue causing the U2021 code