Display shows F4 and the smoker will not start; door icon may flash on the display.

Safety first: Unplug the smoker before working around the door switch wiring.

Check door closure:

• Ensure the smoker door closes fully and the latch engages firmly. Adjust the latch catch if the door is loose.
• Inspect the door gasket for deformation that might prevent full closure.

Locate and test the door switch:

• Depending on model, the door switch may be a small plunger switch in the frame or a magnetic reed switch hidden behind the trim.
• Remove the front trim or side panel to access the switch. Check that the actuator moves freely.
• Disconnect the switch and test continuity with a multimeter while opening and closing the door. The reading should change between open and closed.

Repair: Replace a defective door switch assembly or realign the magnet and reed switch if used. Reseat the door switch connector on the main control board. Once the control senses the door closed, F4 should clear.