LG · Microwave

LG Microwave F4 error code

Difficulty: Hard · Cost: $80–$250 · Duration: Requires professional service

The F4 error means your LG microwave has detected a problem with the humidity sensor — the component that detects steam and moisture levels inside the cavity to automatically adjust cooking time on certain settings. When it fails the microwave cannot use sensor cooking functions correctly. There are no user steps to resolve this error and the unit requires a professional repair service to inspect and replace the faulty humidity sensor.

Common causes

Humidity sensor has malfunctioned or failed completely
Wiring connection to the humidity sensor is loose or damaged
Internal fault in the humidity sensor circuit

How to fix it

1

Unplug the microwave for 1 minute and plug it back in to attempt a reset
2

If F4 returns after resetting the humidity sensor needs inspection and replacement by a qualified technician