Direct answer
On the covered LG refrigerator, FU means a freezer compartment fault — LG's own wording: after 10 minutes of starting, the freezer temperature has not dropped below 3.5 °C, or during operation it has risen above 3.5 °C. First, unplug the refrigerator, wait 60 seconds and reconnect it to a direct outlet — LG is specific that it must not be on a power strip or multiple socket.
Definition versus diagnosis
The display names a detected condition—not an automatically failed part.
What this covers
- LG refrigerator covered by the cited source
- Displayed code or documented alias: FU
- The exact operating state described by the manufacturer
What it does not cover
- ×Another product type or original-manufacturer platform
- ×A visually similar but different code
- ×Internal live electrical, sealed-system, gas, battery-cell or control-board repair
Match every character and the exact product
ReversiblePhotograph the complete display and product label. This record covers FU on LG French-door, side-by-side, bottom-freezer and top-freezer refrigerators; display format and available customer checks vary by model.
Preserve the failure state
ReversibleUnplug the refrigerator, wait 60 seconds and reconnect it to a direct outlet — LG is specific that it must not be on a power strip or multiple socket. Record the operating stage, recent change and what still works before clearing the message.
Correct only the documented fault domain
ReversibleIf the error continues, LG directs you to check the freezer is set to −18 °C, how often and how long the door is opened, whether food is blocking the air vents, and whether the door gaskets seal — testing a gasket by closing a sheet of paper in the door and feeling it resist. Do not borrow a reset or meaning from a similar code, product or model year.
Verify once, then respect the service boundary
ReversibleRepeat only the shortest safe action that reaches the original stage. If FU returns, stop repeated resets and use model-specific manufacturer support.
Evidence ledger
Sources behind this answer
Visible sources support the visible claims. Home Product Support records the publisher, the fact used and the review date; community reports can suggest an issue but do not become a published fact on their own.
Exact questions
Common follow-ups
What does FU mean on a LG refrigerator?+
a freezer compartment fault — LG's own wording: after 10 minutes of starting, the freezer temperature has not dropped below 3.5 °C, or during operation it has risen above 3.5 °C.
Can I reset FU without fixing the cause?+
A reset may hide the display temporarily but does not correct the documented fault. Record the code and complete only the safe checks first.
Why is the complete model number required?+
Manufacturers reuse characters across platforms. The model number determines which official table, controls and service boundary apply.
When should I stop?+
Food safety comes first. If the freezer is not holding temperature, move the food before working through the checks.
Answer for the exact device and software version shown above.