Error handling: Display.
Error reset: Not possible.
Description: This error occurs if saving or loading is performed after the external power supply drops and a power supply abnormality (AC FAIL) is detected in the AVR.
Countermeasures: This error occurs when controller power is interrupted. It can be cleared by switching controller power on again. If it remains, check the relevant items in the power supply circuit (including the AVR) for abnormalities, or replace the power sequence board.