FF refers to an anti-freeze protection state on documented LG models. Exposure to cold helps guide the checks; if it appears in mild conditions, it needs diagnosis.
The front-facing LG documentation links FF to freezing. Not all units have the same temperature limits or the same recovery procedure.
Identify which circuit was exposed
A frozen inlet valve or hose prevents water from entering. Freezing in the tub or drain path can prevent draining. Check the installation and the cold spell without forcing hardened hoses or repeatedly trying to start the pump.
Check your model’s thawing procedure before adding water to the drum or disconnecting a connection. Do not use boiling water, an open flame, a heat gun, or concentrated heat: you could get burned or damage materials and connections.
When the assembly reaches the allowed conditions, inspect externally for any leaks that may have appeared. Restoring flow does not rule out damage caused by ice. Resume only according to the manual and stop using it if there is a leak.
FF without a cold-weather event
Do not add heat to test the explanation. Tell service the approximate room temperature and whether the error appears at startup.
If the washer will stay in a place with a risk of freezing, prepare it for draining and storage following the manual for that specific model.