On the covered Samsung range or oven, C-90, C-91 means the door-lock system did not operate correctly. First, allow complete cooldown and never force the door. Then: arrange latch/motor service. A door that will not unlock is held by the lock motor, so wait for the oven to cool and do not pry it open.
Try in this order
0 of 6 completedWhat to do first
ReversibleAllow complete cooldown and never force the door.
Correct only the documented fault domain
ReversibleArrange latch/motor service.
Let the oven cool before anything else
ReversibleA door that will not unlock after a clean cycle is often waiting for the cavity to cool, so give it time and never pull the door against the latch.
Power the range off for a minute
ReversibleTurn the breaker off for about a minute, or longer if the display stays blank, then turn it back on and press Cancel to see whether the lock resets.
Look at the latch area
ReversibleWith the oven cool, check around the hinge and the latch for baked-on grease or debris that could stop the lock moving, and wipe it clear with a damp cloth.
Call for latch or motor service
ReversibleIf C-90 or C-91 returns, the door-lock motor or latch needs a technician; Samsung's own table points to latch or motor service.
Evidence ledger
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Exact questions
Common questions about “Samsung range or oven code C-90, C-91”
What does C-90, C-91 mean on a Samsung range or oven?+
The door-lock system did not operate correctly.
Can I keep cooking if the door will not lock?+
A faulted door-lock system can stop self-clean from running, and the safest course is to use the oven only for normal baking if the display allows, or to wait for service.
Why would the code appear after a self-clean?+
The lock motor works hardest during a clean cycle, so a worn latch often shows up then. Clearing the code with a power reset only helps if the lock is not physically jammed.