LG · Microwave Moderate

F-3 — Key short / specific button stuck

Similar to F-2, but the control has identified a specific key as stuck closed. Often appears immediately after a spill or steam exposure.

Keep using it?
Yes, with caution
DIY difficulty
Moderate
Verified against
lg.com ↗

How to fix it

  1. Unplug for 10 minutes to dry out condensation.
  2. Inspect the membrane for bubbles, soft spots, or stuck buttons.
  3. Disconnect the keypad ribbon at the control board and restore power. If F-3 clears, replace the keypad. If F-3 persists, replace the control board.
  4. Never use saturated rags on the panel — wipe with a barely damp microfiber.
  5. Replace the touch panel assembly if confirmed faulty.
  6. Test all buttons after reassembly.

Why it happens

Typical signs: F-3 on display at power-up · One button always seems pressed · No response to other keys

  • Liquid intrusion under keypad Soup or steam wicked under the membrane during a previous cook.
  • Physical damage to membrane Cracked overlay holding a contact closed.
  • Sticky residue under the overlay Cleaning product or food sugar bridging contacts.
  • Failed control board scan line PCB falsely reads a key as closed.

Parts you may need

If diagnosis points to a failed part, these are the common replacements. As an Amazon Associate we earn from qualifying purchases.

  • LG microwave touch panel Common replacement
    Amazon →
  • LG microwave main control board Common replacement
    Amazon →

More LG microwave codes

DOOR DOOR / Door Error — Door switch / interlock fault F-1 F-1 — Main Control Board Fault F-2 F-2 — Thermistor / Temperature Out of Range F-4 F-4 — Humidity / steam sensor fault F-5 F-5 — Damper Switch Error F19 F19 — Inverter / High-Voltage Fault

All LG codes → All microwave codes →

Frequently asked questions

What does the F-3 code mean on a LG microwave?

Similar to F-2, but the control has identified a specific key as stuck closed. Often appears immediately after a spill or steam exposure.

What causes the F-3 code on a LG microwave?

Liquid intrusion under keypad: Soup or steam wicked under the membrane during a previous cook. Physical damage to membrane: Cracked overlay holding a contact closed. Sticky residue under the overlay: Cleaning product or food sugar bridging contacts.

Is it safe to keep using a LG microwave with a F-3 error?

Yes, with caution. This is rated a moderate-severity fault.

How do I fix F-3 on a LG microwave?

Unplug for 10 minutes to dry out condensation. Inspect the membrane for bubbles, soft spots, or stuck buttons. Disconnect the keypad ribbon at the control board and restore power. If F-3 clears, replace the keypad. If F-3 persists, replace the control board.

Always unplug an appliance before servicing it. This guide is for informational purposes and is not a substitute for a qualified technician. Verified against manufacturer documentation: lg.com.