LG F12U2HDM Series Service Manual page 5

2-2. WATER LEVEL CONTROL
This model adopts a pressure sensor which can sense the water level in the tub.
Water supply is stopped when the water level reach the preset level, then washing program proceeds.
Spinning does not proceed until the water in the tub reduces to a certain level.
2-3. THE DOOR CAN NOT BE OPENED
While program is operating.
While Door Lock light is on.
2-4. NFC (Tag On Function)
The Tag On function can only be used with smart phones equipped
with the NFC function and based on the Android operating system (OS).
Position your smart phone so that the NFC antenna on the back of
your smart phone matches the position of the Tag On icon on the
appliance.
NFC reading performance of your smart phone must be higher than
a certain level for using this function.