Samsung Range C-21 — What It Means & How to Fix It
Also shown as C21 on some models.
C-21 is Samsung's over-temperature code: the oven sensor detected the cavity hotter than the setpoint and shut heating down to protect the unit.
What this code means
C-21 tells you the cavity temperature climbed above what the sensor was set to — the board saw an over-temperature condition and cut power rather than overshoot dangerously. Occasional causes include a self-clean cycle's heat spike, a sensor that drifts high, or a bake/broil element circuit that stayed energized when it should have opened. Because an element that won't switch off is a fire risk, recurring C-21 deserves a technician quickly.
Samsung's official materials describe C-21 as the oven's over-temperature readout (on the microwave side the same number is the 'temperature is high' warning). If C-21 appears mid self-clean, Samsung's guidance is to let the cavity cool fully before restarting. Model number is on the frame behind the storage drawer.
Most likely causes
| Cause | How likely | DIY-fixable? |
|---|---|---|
| Bake or broil element relay stuck on the control board | Common | No — technician job |
| Blocked heat path — vent covered or cavity overcrowded | Common | Yes — clear the vent |
| Temperature sensor drifting high | Occasional | No — technician job |
| Heat spike during a long self-clean cycle | Occasional | Yes — cool and retry |
What you can try yourself
- Turn the oven off and let the cavity cool completely before doing anything else — C-21 is a heat-protection code.
- Check nothing is covering the vent on the back of the cooktop and that no foil, pan, or baking sheet blocks airflow around the oven.
- Restart the oven at your previous setting. A single spike that doesn't return usually needs no further action.
- If C-21 repeats, stop use and book a technician: a stuck element relay keeps heating even when the board commands off.
When to call a technician
- C-21 returns on normal baking temperatures, not just during a hot self-clean.
- The element glows or the cavity heats with the oven turned off.
- Smoke, a burning smell, or food scorching far beyond the set temperature.
Typical professional repair cost: No cost if a one-off spike; a stuck-relay board or element repair typically runs $150–$400 including labor.
Frequently asked questions
Is C-21 the same as a temperature sensor failure?
Not exactly. C-20 is the sensor circuit failing to read; C-21 means the sensor read a real over-temperature. C-21 is the more safety-relevant one, because it can mean heating stayed on when it shouldn't.
Why does my Samsung range throw C-21 during self-clean?
Self-clean deliberately runs the cavity far hotter than normal, and on marginal units the sensor's reading can overshoot the control window. If the code only ever appears in self-clean, cooling and retrying usually ends it.
Can a dirty oven cause C-21?
Indirectly — heavy grease or a foil-lined floor changes how heat distributes in the cavity and can push readings toward the upper limit. Cleaning the cavity and removing foil sometimes stops recurring over-temperature codes.
Sources checked
Error meanings can vary by model. This guide was checked against the documentation above; use the manual for the model number on your own appliance when it differs.
Related Samsung codes
- Samsung Range C-24 C-24 is Samsung's fast-temperature-rise warning: the cavity heated quicker than expected, most often because the vent on the back of the cooktop is covered.
- Samsung Range C-20 C-20 is Samsung's oven temperature sensor error: the sensor circuit reads open, shorted, or out of range, so the control board can't trust the cavity temperature.
- Samsung Range C-F0 C-F0 is Samsung's communication error between the main control board and the display: the two stopped talking. A restart clears most cases; induction models have an official software-update fix.
- Samsung Range S-01 S-01 is Samsung's safety shutoff: the oven ran continuously at its set temperature for hours and the board switched it off. It's a protection feature, not a fault — turn it off, remove the food, and use it normally.
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