LG Microwave F5 Error — Door Switch Fault Fix

What Does This Error Mean?

F5 on LG microwaves is a door switch fault — the unit can't tell whether the door is open or closed reliably.
This is safety-critical: the microwave refuses to operate until door state is confirmed.
Open and close the door firmly several times — most F5 events clear after a clean close.
If F5 persists, the switch or hinge needs service-tech repair.

Affected Models

LG over-the-range microwave
LG countertop microwave
LG NeoChef
LG LMV series

Common Causes

Door not closing fully — hinge or alignment issue
Door switch arm bent away from contact
Switch contacts welded together
Wiring loose at the switch
Door latch worn out

How to Fix It

Open and close firmly.

Open the door fully, push it closed firmly until you hear the click.
Repeat 5–10 times.
The door switch arm needs clean activation — sometimes it just needs to be exercised to start working again.
Listen for the click each time.
Check the door for sag.

Look at the gap between door and body when closed.
Should be even all around.
If the door sags downward, hinges are loose or worn.
Built-in models can be re-shimmed; countertop units usually need hinge replacement.
Inspect the door latches.

Two plastic prongs on the door go into matching holes in the body when closing.
Look at the prongs — any cracks, breaks, or wear?
Worn prongs prevent good door closure and trigger F5.
Replacement prongs run 20–40 USD.
Don't open the microwave for repair.

Door switches and their wiring sit inside the microwave near high-voltage components.
Microwave capacitors are dangerous — service-tech-only territory.
Don't try to access the switch even when unplugged.
Schedule LG service.

Provide model and serial numbers.
Switch replacement is 1–2 hours typical labor.
Out of warranty: 100–200 USD all-in.
Free under warranty.
Worth doing for safety — F5 makes the microwave unusable.

Frequently Asked Questions

Why is the door switch a safety issue?

If the magnetron operates with the door open, microwave energy escapes the cavity.
The switch confirms the door is closed before allowing the magnetron to run.
Without confirmed closure, F5 prevents operation entirely — that protection is doing what it should.
Don't try to bypass.

Can a worn hinge cause F5 even though the switch is fine?

Yes — if the door doesn't close in the same exact position every time (because the hinge is worn), the switch may not engage reliably.
Replacing the hinge fixes F5 in this case, even though the switch itself is functional.
The technician will diagnose the actual cause during the visit.