Written by
Maren Coleman Appliance Care EditorPublished October 29, 2026
VERIFIED
Error codeE21
ApplianceMicrowave
Open circuit at the thermal sensor
The control board received an open report from the thermal sensor circuit, and that is what E21 signals. On an over-the-range microwave the possible sources are the sensor itself, the Appliance Control Board, or wiring between them.
Try the breaker
Cut the power at the breaker for a minute.
Turn the power on again.
Keep an eye on the display for one minute and see if E21 comes back.
If E21 returns, Whirlpool microwave repair covers San Francisco and the Bay Area; call (415) 687-4102. Tell us the code, the model number and what the reset did.
Model compatibility: Whirlpool reuses codes across series and model years, so E21 may mean something different on another appliance or generation. Confirm this against your model’s documentation and record your full model number before acting.
Plain language
What this code means
E21 means the thermal sensor circuit reported open to the control board.
Important safety warning. Do not attempt repairs involving electrical components, gas, water lines, refrigerant or sealed systems. Unplug the appliance if it is safe to reach the outlet, and leave internal diagnostics to a qualified technician.
Seeing this code on your Whirlpool appliance?
Book a specialist visit for a clear estimate and approval before any repair.
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