Written by
Nadia Okafor Appliance Care EditorPublished October 26, 2026
VERIFIED
Error codeC-21 / C21
ApplianceMicrowave
In Samsung’s microwave table, C-21 (also C21) is described as an error with the temperature sensor, exactly like C-20 and C-22. It sits in the list for current-generation models.
Reset sequence
Cut the supply: unplug the unit or flip its breaker.
If liquid or cooktop steam has gotten into the unit lately, give it time to dry out completely.
No moisture involved? Count off 60 seconds, then restore power.
A C-21 that stays is worth a call to (415) 969-6153. Our Samsung microwave repair team covers San Francisco and the Bay Area, and it helps to have the code, the model number and the steps you tried to hand.
Model compatibility: Samsung reuses codes across series and model years, so C-21 / C21 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
C-21 reports an error with the temperature sensor on a current-generation Samsung microwave.
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 Samsung appliance?
Book a specialist visit for a clear estimate and approval before any repair.
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Replacement parts are selected for the exact model and confirmed with you before ordering or installation.
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