Error Code C-21
Oven overheating - internal temperature critically high
Critical
Stop using immediately - risk of damage or safety issue
Also displayed as: C-21
What This Means
Oven sensor resistance out of specification; Defective broil, bake, or convection heating element; Failed relay on main PCB not cutting off heat; Wire harness disconnected on main PCB; Oven sensor connector resistance out of spec
What actually causes this:
Temperature sensor not reading correctly, heating element stuck on, or relay failure causing uncontrolled heating
First Thing to Check
Disconnect power and measure oven sensor resistance - must be 1080 Ohms at room temperature
Parts Involved
How to Fix
- 1
Disconnect power and disconnect sensor harness from sensor
- 2
Measure sensor resistance: should be 1080 Ohms at room temperature
- 3
Check broil, bake, and convection heater resistances
- 4
Verify DLB, broil, bake, convection relays operate normally
- 5
Check main PCB for disconnected wire harnesses
- 6
Measure oven sensor connector resistance on main PCB (normal 2850 Ohms)
- 7
Follow diagnostic steps on page 35 for detailed relay testing
This Error Applies To
Samsung DOB30M977 Series Ovens & Ranges (2017) (2017–present)
Related Error Codes
Touch panel control communication failure
PCB temperature sensor open or short circuit
Cooling fan motor malfunction
Oven temperature sensor circuit is open
PCB overheating - internal temperature critically high
Meat probe sensor short circuit detected
Steam drain system not working - water remains after cycle
Door lock mispositioned or malfunctioning