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 sends a negative response to the erase memory or checkdependency command during the ECU upgrade.
2. This error usually appears when the software being installed does not match the ECU specifications.

Solution: 

1. Verify whether the ECU upgrade was performed in Automatic Mode or Manual Mode.
2. If the upgrade was performed in Manual Mode, verify that the correct ECU subcategory was selected for the applicable ECU.
3. Check whether any aftermarket equipment is installed in the vehicle.
4. Verify that all upgrade conditions are met. For 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.