Safety: Disconnect power before removing any panels.

Confirm door operation: Open and close the door several times. Listen for a distinct click from the door switch. If no click, the switch may be stuck or broken.
Inspect latch and strike: Ensure the door strike lines up with the switch actuator. Replace any cracked or missing latch components.
Access and test door switch: Remove the top panel and front panel as needed. Disconnect the door switch connector and test with a multimeter for proper continuity when actuated.
Check harness: Follow the harness from the switch to the main PCB. Look for pinched, cut, or burnt wires and reseat all connectors.
Replace components: If the switch or latch is defective, install a new Samsung door switch or door latch kit. If wiring and switch are good but dF persists, the main PCB may need replacement.

Note: PCB replacement should generally be done by a qualified technician due to cost and risk of misdiagnosis.

Dryer will not start; display shows dF; door appears closed but cycle will not begin.

Possible Causes