LG oven displays F9 and the door may remain locked or the self-clean cycle will not start/stop.

Safety first: Turn off power at the breaker. The door lock mechanism can move unexpectedly when powered.

• Allow cooling: If the error occurred during self-clean, wait until the oven is completely cool. Sometimes the lock will release automatically once temperature drops.
• Try a reset: With the oven cool, turn the breaker OFF for 5 minutes, then ON. Attempt to start and then cancel a clean cycle to see if the lock cycles.
• Access lock assembly: For freestanding ranges, remove the rear top panel to access the door lock motor assembly. For wall ovens, you may need to pull the unit out slightly and remove the top cover.
• Inspect lock mechanism: Check for bent latch, broken plastic parts, or obstructions. Manually move the latch arm to verify it is not seized.
• Test lock motor and switch: Disconnect the lock motor connector and measure resistance across the motor terminals (should not be open). Check continuity of the lock position switch when the latch is in locked vs unlocked positions. Replace the lock assembly if motor or switch is faulty.
• Check wiring: Inspect harness from lock assembly to control board for damage or loose connectors. Repair as needed.