Written by
Adrian Soto Appliance Repair Content SpecialistPublished September 5, 2026Updated October 20, 2026
Error codeC-21 / C21
ApplianceMicrowave
Quick answer
C-21 (C21) is an error with the temperature sensor on a Samsung microwave. Unplug, let it dry or wait, then request service if it returns.
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 is an error with the temperature sensor on a Samsung microwave.
Samsung’s microwave table lists C-21 (C21) as an error with the temperature sensor. Samsung’s current-generation microwave list includes it.
About the C-21 display
Samsung’s list gives one description, an error with the temperature sensor, for C-20 and C-22 together.
First steps
Start by removing power, either at the plug or at the breaker.
Had a spill, or steam from a cooktop, reached the controls lately? Allow time for everything to dry.
Dry already? Pause for 60 seconds, then turn the microwave on.
A code that returns means it is time to ask for service.
Our Los Angeles team handles Samsung microwave calls, and you can reach it at (310) 896-4231. Have the code (C-21), the model number and the steps you already tried ready when you call. More on microwave repair.
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.
