Samsung Microwave Error C-21
⚡ Quick Answer: The Samsung Microwave error C-21 indicates an abnormal internal temperature, typically due to a malfunction in the magnetron or temperature sensor. Th... ✅ DIY Fixable
What Does Error C-21 Mean?
The Samsung Microwave error C-21 indicates an abnormal internal temperature, typically due to a malfunction in the magnetron or temperature sensor. This error often occurs during or after the heating cycle, causing the microwave to stop cooking and display the C-21 code. Unusual humming sounds may accompany this issue. To resolve, allow the unit to cool down and perform a basic reset. If the error persists, professional inspection is recommended.
Common Symptoms:
- Error displays during or after heating cycle
- Microwave stops cooking and shows C‑21
- Unit may cool down before restarting
Possible Causes
- Abnormal internal temperature detected by sensor (high)
- Faulty temperature sensor/thermistor or its wiring (medium)
How to Fix Error C-21
DIY Fix Basic reset and cooling
- Disconnect microwave from power outlet
- Wait for at least 10–30 minutes to allow unit to cool down
- Reconnect power and test operation
DIY Fix Inspect for overheating triggers
- Ensure vents are not blocked and microwave has adequate ventilation
- Avoid prolonged continuous use that may overheat the appliance
- Check that the unit is on a stable, flat surface
Technician Only Temperature sensor/thermistor and wiring inspection
- Disconnect power and remove outer cabinet (technician only)
- Check temperature sensor/thermistor leads and connector for damage or loose wires
- Measure sensor resistance with multimeter to verify within expected range
- Replace sensor or repair wiring as needed
Parts needed: Temperature sensor/thermistor, Wiring harness/connectors
Technician Only Control board diagnostic
- If sensor and wiring check OK, test control board diagnostics for false high temperature reading
- Replace main control board if confirmed defective
Parts needed: Main control board
- Error repeats after reset and cooling period
- Unit shows signs of overheating (smoke, burning smell)
- Temperature sensor inspection is beyond user skill level
Next step
Choose the next step for C-21
Confirm the diagnosis before ordering. An error code can identify the system involved, but it does not prove that a specific part has failed.
Most relevant component to inspect
Temperature Sensor
Monitors the internal temperature to ensure correct operation and prevent overheating.
- Typical part-only price
- $15 - $35
- DIY difficulty
- Easy
- Estimated time
- 15-30 mins
Where can I find the model number?
Check the rating label around the door, lid, frame, rear panel, or inside the appliance cabinet. Use the complete model number, including suffixes.
Verify the complete model and part number on the retailer's compatibility page before ordering.
Other parts options
Check related components first; use model search as a fallback.
Thermistor
Measures precise temperature changes and sends resistance feedback to the control board.
Wiring Harness
Connects controls, sensors, motors, and other electrical components inside the appliance.
Main Control Board
The central brain of the appliance that controls all components, cycles, and timings.
Model-compatible Microwave parts
Enter the complete model number to browse compatible replacement parts. This is a model-based parts search, not a diagnosis that a specific component failed.
Affiliate disclosure: As an Amazon Associate I earn from qualifying purchases. We may earn a commission from other qualifying purchases or service requests made through links on this page, at no additional cost to you. Recommendations are based on repair relevance, not commission rate.
Technical Specifications
| wattage | 1000W |
|---|---|
| component | Magnetron |
| resistance | 10-30 ohms |
| part_number | DE74-20019A |
| voltage_rating | 120V AC |
Common Questions
What does C-21 error mean on Samsung Microwave?
C-21 indicates an abnormal internal temperature, often related to the magnetron or temperature sensor malfunction.
Can I fix Samsung Microwave C-21 error myself?
Yes, you can perform a basic reset and check for overheating triggers like blocked vents.
How much does it cost to fix C-21 error?
The estimated repair cost ranges from $30 to $120, including parts and labor.
When should I call a technician for C-21?
Call if the error recurs after a reset, or if you notice signs of overheating like smoke or burning smells.
Sources & References
Data last verified: 2026-07-22
User Comments (0)
Share your experience or solution below.
Please login to post a comment.
Be the first to comment!