What do you have plugged into the inverter outlet? Unplug everything and disconnect power from the inverter. Reconnect power and see if the code returns. That inverter is a modified sine wave model and certain things cannot be connected to it. They either won't work or will overload it. Also it is only a 1,000 watt unit so no large power drawing appliances. It is typically designed to run the TV and related equipment when the generator isn't running. Another possible cause could be undersized 12v DC supply wiring. Depending on the length of run you may need 1 gauge or larger wire.