What does LG microwave error code F-4 mean?

F-4 means the humidity sensor is malfunctioning. Clean the microwave interior (especially the ceiling area) and unplug for 1 minute. Professional repair is required if the error persists.

F-4

LG Microwave Error Code F-4 — Humidity Sensor Error

Advanced Fix N/A (professional repair needed) No tools needed

What this means

The F-4 error code indicates a problem with the humidity sensor inside the microwave. The humidity sensor detects moisture levels in the cooking cavity to automatically adjust cook times in sensor cooking modes. A failed sensor, dirty sensor lens, or wiring issue can trigger this code.

Alternate codes: F4

Step-by-step fix

2 steps

Clean the interior

Clean the microwave interior thoroughly, paying attention to the ceiling where the humidity sensor is usually located. Food splatter can interfere with sensor readings.

Unplug and reset

Unplug the microwave for 1 minute, then plug it back in.

When to call a professional

This error requires professional service. Microwave repair is dangerous due to high-voltage capacitors. Do not attempt to open the cabinet.

Information compiled from manufacturer service manuals, official troubleshooting documentation, and appliance repair industry resources. This guide is for informational purposes only — always consult a qualified technician for complex repairs.

Learn more about our sources

Parts you may need

Humidity Sensor Assembly

Part #6501W1A013A · $20–$40

If the sensor has failed

Find Part

Links may earn us a commission at no extra cost to you. We only recommend parts relevant to this repair.

Quick Info

BrandLG

ApplianceMicrowave

Error CodeF-4

DifficultyAdvanced Fix

Est. TimeN/A (professional repair needed)