GE Microwave F4 — What It Means & How to Fix It
F4 means the humidity sensor circuit reads open — the sensor that tracks steam during cooking isn't reporting, so the oven locks out.
What this code means
GE defines F4 as an open humidity sensor. The sensor that measures steam in the cavity (used by auto/sensor cook programs) reads as disconnected, so the oven can't trust its cooking logic.
F4 appears when you select a sensor/auto cook cycle, or at startup on some models, and returns consistently rather than clearing itself.
Most likely causes
| Cause | How likely | DIY-fixable? |
|---|---|---|
| Humidity sensor failed open | Common | no |
| Sensor connector or wiring fault | Less common | no |
| Intermittent glitch after a power event | Occasional | yes |
What you can try yourself
- Reset the breaker for 30 seconds and retry with a simple manual cook cycle — if manual cooking works, the fault is limited to the sensor circuits.
- Try a sensor/auto cycle once more to see if F4 returns.
- If it does, call a technician — the humidity sensor lives inside the cabinet, and its replacement isn't a DIY job.
- Mention the code when booking so the tech brings the right sensor.
When to call a technician
- F4 returns immediately after the breaker reset
- Every sensor/auto cook cycle stops with F4 before cooking
Typical professional repair cost: Service visit, typically $100–$250 for a humidity sensor replacement; $0 if the reset clears a one-time glitch.
Frequently asked questions
Can manual cooking still work with F4 up?
Usually yes, because F4 only affects the sensor-based cycles. But the oven should still be serviced so the sensor logic is trustworthy again.
Is the humidity sensor the same as the thermal sensor?
No — they're separate parts. F1/F2 point at the thermal (temperature) sensor; F4/F5 point at the humidity (steam) sensor.
Sources checked
Error meanings can vary by model. This guide was checked against the documentation above; use the manual for the model number on your own appliance when it differs.
Related GE codes
- GE Microwave F1 F1 means the thermal sensor circuit reads open — or the oven detected excessive heat. Cool it down and try the 30-second reset.
- GE Microwave F2 F2 is a shorted thermal sensor fault — the sensor circuit reads closed when it shouldn't, so the oven locks out.
- GE Microwave F3 F3 means the touch pad is reading as shorted — often a key pressed over 60 seconds or moisture on the pad.
- GE Microwave F5 F5 means the humidity sensor reads shorted — the steam sensor is stuck in one state, so sensor-cook cycles lock out.
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