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