Error code
C-21
Meaning
Oven sensor shorted / Oven heating over
Moderate
What to do
Why this happens
The issue may stem from a failed oven sensor, broil heater failure, bake heater malfunction, convection heater problem, DLB relay breakdown, main PCB defect, or harness disconnection.
SourceSamsung service manual - 30" Freestanding Electric Range