Error Code Occurs During ECU Upgrade (5021-31-7F33)

September 02, 2026 14:34 Updated

Symptom: Error code [5021-31-7F33] occurs during an ECU upgrade.

Cause: The control unit sends a negative response to the Erase Memory or CheckDependency command during the ECU upgrade.

Solution:

1. Verify whether the ECU upgrade was performed in Automatic Mode or Manual Mode.
2. If Manual Mode was used, verify that the ECU upgrade was attempted using the correct subcategory for the control unit.
3. Check whether any aftermarket equipment is installed in the vehicle.
4. Check whether any work has been performed on the gateway installed in the vehicle.
5. If the issue persists, contact the control unit manufacturer or the Kia Technical Center.