Error code
E-21
Meaning
Oven sensor circuit open condition
Critical
What to do
Why this happens
Possible causes include an oven sensor disconnection, open circuit in sensor wiring, corrosion or damage to sensor terminals, or disconnections at Main PCB connector CN201 or Sub PCB connector CN02.
How to fix it
If connectors are secure, measure sensor resistance - if over 1200 ohms, replace oven sensor
SourceSamsung service manual