LG Microwave F3 Error — Shorted Key Fix

What Does This Error Mean?

LG microwave F3 error means a button on the control panel is stuck or shorted — the touchpad is sending a continuous key signal to the control board. A power reset sometimes clears it — if F3 returns, the touchpad needs replacing.

Affected Models

LG Over-the-Range Microwave
LG Countertop Microwave
LG LMV Series
LG LMC Series
LG LMVH Series

Common Causes

Worn or degraded touchpad membrane with a stuck key contact
Moisture or steam condensing under the control panel
Grease buildup on or under the touchpad surface
Physical damage to the control panel

How to Fix It

Perform a power reset.

Unplug the microwave for 60 seconds, then plug it back in. F3 caused by temporary steam or moisture often clears after a full power cycle.
Clean the control panel surface.

Wipe the touchpad area with a soft, slightly damp cloth and dry completely. Grease or moisture seeping under the edge of the panel can hold a key contact closed.
Identify which key is shorted.

After restoring power, observe whether any button appears lit or active that you have not pressed. The stuck key is usually the cause of F3 — cleaning or replacing that specific membrane area resolves the error.
Replace the touchpad membrane.

Order the touchpad for your specific LG model number (on the label inside the door frame). The membrane peels off or unclips from the front panel and connects via ribbon cable to the control board.

When to Call a Professional

LG microwave touchpad replacement is a straightforward parts swap on most models. If you are not comfortable with disassembly, a technician can replace the membrane quickly.