F4
GE Microwave
Severity: ModerateWhat Does This Error Mean?
GE microwave error F4 means the humidity (moisture) sensor has a fault — the sensor that many GE microwaves use to automatically detect when food is cooked by measuring the steam it releases. F4 is less critical than F1 or F2 — the microwave can sometimes still operate on manual cook modes. A power reset and a thorough cleaning often clear F4 without any parts replacement.
Affected Models
- GE Profile Microwave
- GE Cafe Microwave
- GE Spacemaker
- GE JES Series
- GE JVM Series Over-the-Range
Common Causes
- Grease or food residue coating the humidity sensor face and blocking accurate steam readings
- Humidity sensor component has failed and is reading out of range
- Humidity sensor connector loose or corroded from moisture exposure
- Sensor wiring damaged inside the microwave cavity from heat or grease
- Control board fault misinterpreting the humidity sensor signal
How to Fix It
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Unplug the microwave for 30 seconds and power back on.
F4 is one of the error codes most likely to be cleared by a power reset — a brief transient reading from food steam during the last cook cycle can trigger a one-off fault. If F4 does not return after the reset, no further action is needed.
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Clean the inside of the microwave thoroughly, paying particular attention to the humidity sensor — a small protrusion or window typically located near the top of the cavity interior.
A film of grease or food residue on the sensor face prevents accurate steam detection. Wipe the sensor gently with a damp cloth (microwave unplugged), then dry completely before powering back on. Avoid abrasive scrubbers that could damage the sensor surface.
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After cleaning, test the auto sensor cook function (if your model has it) by heating a cup of water on a sensor cook setting and confirming it completes without triggering F4.
A successful sensor cook test confirms the cleaning resolved the issue. If F4 appears only on sensor cook modes but not on manual timed modes, the sensor has degraded and should be replaced before it fails completely.
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If F4 returns consistently after cleaning and resetting, the humidity sensor requires replacement — contact GE Appliances Parts with your model number for the correct sensor component.
The humidity sensor on most GE microwaves is accessible from inside the cavity without touching high-voltage components. However, if you are not confident in the repair, have an authorised technician replace it.
Frequently Asked Questions
What does the humidity sensor do in a GE microwave?
The humidity sensor detects the amount of steam released by food as it cooks. Many GE microwaves use this to automatically determine when food is done — the sensor cook feature stops the cycle when it detects that steam output has peaked and then started to fall, which indicates the food has reached temperature. Without a working sensor, auto-cook functions are unavailable but timed manual modes still work normally.
Can I still use my GE microwave if F4 is showing?
On most GE models, F4 disables sensor cook modes but manual timed cooking modes continue to work. If the microwave locks out completely with F4 active, treat it like F1 or F2 and have it inspected before use. Check your model's user manual for whether manual modes remain available when F4 is active.