LG Microwave Error Code F4: Meaning, Causes, and Easy Fixes

What Does LG Microwave Error Code F4 Mean?

If your LG microwave suddenly shows the F4 error code, it usually points to a humidity sensor or temperature sensor issue.

This sensor helps the microwave detect steam and heat levels to cook food properly. When it fails or sends incorrect signals, the appliance stops working and displays F4.

Common Causes of LG Microwave F4 Error

Here are the most common reasons behind this error:

1. Faulty Humidity Sensor

The sensor may be damaged or worn out over time, especially with heavy usage.

2. Loose or Damaged Wiring

Internal wires connecting the sensor to the control board might be loose, burnt, or disconnected.

3. Control Board Malfunction

Sometimes the issue is not the sensor but the main PCB (control board) failing to read signals correctly.

4. Moisture Build-up Inside Microwave

Excess steam or water inside the microwave can temporarily confuse the sensor.

How to Fix LG Microwave Error Code F4

Try these solutions step by step:

1. Power Reset (Quick Fix)

• Unplug the microwave

• Wait for 5–10 minutes

• Plug it back in

👉 This resets the system and may clear temporary glitches.

2. Clean the Interior

• Wipe off any moisture inside the microwave

• Make sure the vents are dry and clear

👉 This helps if the issue is caused by excess steam.

3. Check Sensor Connections

⚠️ Only do this if you’re comfortable opening appliances.

• Remove the outer cover

• Locate the humidity sensor

• Check for loose or burnt wires

👉 Reconnect or replace damaged wiring if needed.

4. Replace the Humidity Sensor

If the sensor is faulty, replacing it is usually the best solution.

• Order a compatible LG sensor

• Install it carefully or call a technician

5. Call Professional Service

If the error persists, the issue may be with the control board.

👉 In this case, it’s best to contact LG customer support or a certified technician.

When Should You Be Concerned?

You should take the issue seriously if:

• The error appears repeatedly

• The microwave stops heating

• You notice burning smells or unusual sounds

Can You Still Use the Microwave?

No. It’s not recommended.

Using the microwave with an F4 error can lead to:

• Improper cooking

• Further internal damage

• Safety risks

Final Thoughts

The LG microwave F4 error code is usually related to a sensor issue, and in many cases, it’s fixable with simple steps like resetting or cleaning.

If the problem continues, replacing the sensor or calling a professional is the safest move.

Quick Summary

• Error Code: F4

• Meaning: Humidity/temperature sensor problem

• Easy Fix: Power reset + cleaning

• Advanced Fix: Replace sensor or repair wiring