On the covered KitchenAid over-the-range microwave, E21 means a temperature sensor in the microwave has reported a fault First, unplug the microwave for a minute and let it cool. Then: run a cup of water for a minute to test it, and book service if E21 returns, since the sensor and the control are for a technician.
Differential
Likely causes of “KitchenAid over-the-range microwave code E21”, and how to tell them apart
- 1
A temperature sensor in the microwave has reported a fault
What separates it The microwave shows E21 and stops or refuses to start
How to confirm Unplug the microwave for a minute and try again
- 2
A thermistor that reads open or shorted
What separates it The code returns every time the microwave warms
How to confirm A technician tests the thermistor
- 3
Wiring or a connector to the sensor loose
What separates it The code came after the microwave was moved
How to confirm A technician reseats the connectors
- 4
A hot cavity after a long cook
What separates it The code appears right after heavy use
How to confirm Let the microwave cool for half an hour
- 5
A control board fault
What separates it Sensor and wiring test well
How to confirm The board is replaced last
Before you touch a setting
Record this first — changing settings destroys the evidence
- Whether E21 appeared in microwave or convection mode
- How long the microwave had been running before the code showed
- Whether the vent and the filters under the microwave are clear
- The model number from the label inside the door frame
Try in this order
0 of 9 completedWhat to do first
Reversibleunplug the microwave for a minute and let it cool.
Correct only the documented fault domain
ReversibleRun a cup of water for a minute to test it, and book service if E21 returns, since the sensor and the control are for a technician. A power reset is the whole of what KitchenAid publishes for this code: remove power for 1 minute, restore it, and watch whether the code returns.
Unplug the microwave for a minute
ReversiblePull the plug and wait a full minute so that the control restarts, and a one-off sensor reading is cleared.
Let it cool if you cooked for a long time
ReversibleHeat can trigger a temperature fault, so wait half an hour with the door open before trying again.
Plug it in and test with a cup of water
ReversibleHeat a cup of water for a minute. If it warms and no code shows, the fault was a one-off.
Note whether it was in microwave or convection mode
ReversibleOn a convection model the code can belong to the convection side, so tell the technician which mode was in use.
Check the vents and the filters
ReversibleOn an over-the-range model, make sure that the vents and the grease filter are clear, since poor airflow raises the temperature.
Book service if E21 returns
ReversibleA technician tests the temperature sensor and its wiring and replaces the sensor or the control board.
Wash the grease filter
ReversibleSlide the filter out from under the microwave, wash it in hot soapy water, dry it and refit it. A clean filter lets the microwave and the range vent freely.
Model-specific
What is true of this model and not of its siblings
- The code on this page
- E21, a sensor fault.
- Parts involved
- The temperature sensor, its wiring and the control.
- Safety
- Never open a microwave case.
- Convection models have more sensors
- A KitchenAid convection microwave bakes as well as heats, so it carries a thermistor in the oven cavity and another near the heater. The E codes in this group name which sensor misreported. If your model is a plain microwave, the sensor is the cavity thermistor, and a failure there is less common.
- Over-the-range heat
- A microwave mounted over a range sits in rising heat and steam. A clogged grease filter or blocked vent keeps that heat in the cabinet and can push the sensors out of range, so cleaning the filter is a sensible check before any repair.
Stop boundary
When this stops being a self-service repair
- !A KitchenAid microwave that shows E21 after a cool-down and a one-minute unplug should be seen by service with the model number
- !Leave the case closed, because the high-voltage capacitor stays charged after unplugging
- !Do not use the convection mode while a sensor code is open
Evidence ledger
Sources behind this answer
Exact questions
Common questions
What does E21 mean on a KitchenAid over-the-range microwave?+
a temperature sensor in the microwave has reported a fault
Can I reset it myself?+
Unplugging the microwave for a minute can clear a one-off.
Is the microwave dangerous with E21?+
It normally stops itself, but never open the case, because of the stored charge.
Does it still heat?+
It may not until the sensor fault is cleared.
Is E21 the same as E22?+
They are neighbors in the same group and take the same first steps.
Can I clean the grease filter myself?+
Yes, it slides out from the underside, and a wash in hot soapy water restores it.