Maytag Microwave Error Code F4 — Humidity Sensor Failure
What this means
The F4 error code (also shown as F4E4 or F3H on some models) indicates the humidity sensor inside the microwave has failed. This sensor detects steam and moisture levels to automatically adjust cooking time in sensor-cook modes. When it fails, auto-cook and auto-reheat features will not work correctly, though manual cooking modes may still function.
Alternate codes: F-4, F4E4, F3H
Step-by-step fix
4 stepsReset the microwave
Turn off the circuit breaker for 1 minute, then restore power. Test by running a sensor cook cycle.
Clean the interior of the microwave first — grease buildup on the sensor can cause false readings.
Clean the sensor area
Wipe down the inside of the microwave, especially the vent area where the humidity sensor is located (typically at the top of the microwave cavity).
Use a mild cleaner — avoid spraying directly on the sensor.
Test manual cooking modes
Try running the microwave in manual (timed) mode. If it heats food normally, the issue is isolated to the humidity sensor.
You can continue using the microwave in manual mode while waiting for repair.
Schedule sensor replacement
The humidity sensor will need to be replaced by a qualified technician due to the high-voltage components inside the microwave.
This is a less urgent repair since manual cooking still works.
When to call a professional
While you can use the microwave in manual mode, the humidity sensor should be replaced by a professional technician for safety.
Related error codes
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.
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