Error Code [5021-31-7F22] Occurs During KDS 2.0 ECU Upgrade

Symptom:  Error code [5021-31-7F22] occurs during an ECU upgrade.

Cause:

1. The ECU returns a negative response to the erase memory or checkdependency command during the ECU upgrade.
2. This error generally occurs when the software being installed is incompatible with the ECU specifications.

Solution: 

1. Confirm whether the ECU upgrade was performed in Auto Mode or Manual Mode.
2. If the upgrade was performed in Manual Mode, confirm that the ECU upgrade was attempted using the correct subcategory for the ECU.
3. Check whether any aftermarket equipment is installed in the vehicle.
4. Confirm that all upgrade conditions are met. Example: Perform the upgrade with IG On and check the 12 V battery state of charge.

If the issue persists, contact the ECU manufacturer or the vehicle R&D center.