Cause : Option fault comes when the inverter output is shut off when a contact failure occurs between the inverter and the plug-in option. Appears when the switch for manufacturer setting of the plug-in option is changed

1. Check that the plug-in option is plugged into the connector properly.
2. Check for excessive noise around the inverter.
3. Check if the communication option is connected to the connector.
4. Connect the plug-in option securely.
5. Connect the communication option to the connector.