Samsung Oven Error Code C-21
The oven's internal temperature ran away upward. On current models this code frequently traces back to a heat-damaged temperature sensor after a self-clean cycle; the board is the less common, more serious cause.
Common causes
- A faulty oven sensor reads low, so the oven keeps heating (a very common result of sensor damage during self-cleaning)
- A heater relay on the main board has stuck on
- Blocked vents are trapping heat around the oven
What to check, in order
- Turn the oven off and let it cool completely before restarting anything.
- Check that the oven vent and cooling vents are not blocked.
- Restart after switching the power off for at least 30 seconds.
- Test the oven temperature sensor with a meter: about 1,080 ohms at room temperature is normal; replace it if it reads far off or open.
- If the sensor is good and the oven still overheats, stop using it and book service: the main board is not switching the heat off.
Clear the code and test
- Fix what the checks above found first. Clearing the code without fixing the cause only brings it back.
- Plug the appliance back in and restore its water supply if it has one.
- Run the shortest programme and watch the point where the code appeared before.
- If the programme finishes with no code, the fault is cleared. If the code returns, write it down before calling a technician — it speeds up the diagnosis.
When to call a professional
Most cases are solved by the checks above. Book a technician if any of these apply:
- The code comes back after you have run the checks and a test cycle.
- You smell burning, see sparks or scorch marks, or the breaker trips.
- Water is leaking and you cannot stop it at the tap.
- The fix needs panels opened beyond what your manual describes, or a part tested with a meter, and you are not set up for that.
When you call, give the brand, the code C-21, your model number (on a label inside the door or on the back) and the checks you already ran. It shortens the visit.
Parts that may be involved
Oven temperature sensorMain control board
Parts are model-specific. Find your model number first — usually on a label inside the door, on the door frame or on the back — and match the part to that number before ordering.
Questions people ask about C-21
What does C-21 mean on a Samsung oven?
C-21 means: Oven temperature is rising abnormally high (overheating). The oven's internal temperature ran away upward. On current models this code frequently traces back to a heat-damaged temperature sensor after a self-clean cycle; the board is the less common, more serious cause.
Can I fix Samsung C-21 myself?
Start yourself: the checks on this page cover the causes you can reach without opening the machine up. If they point to a faulty part, testing or replacing it is usually a technician job.
How do I clear Samsung C-21?
Fix the cause first — clearing the code on its own brings it straight back. Then restore power and water, run the shortest programme, and watch the stage where the code appeared. If the programme finishes with no code, it is cleared.
Sources checked
- Samsung support: washing machine information codes
- Samsung support: dishwasher information codes
- Samsung support (US): dishwasher troubleshooting
The meaning and checks for this code were checked against the sources above in November 2026. Codes vary by model and region; if your manual lists a different meaning for your exact model, follow the manual.