E12 displayed and door alarm sounds even when the door is closed

Safety first: Disconnect power before working around electrical switches.

Steps:

• Locate the door switch, usually mounted in the door frame or ceiling of the freezer opening.
• Press the switch plunger by hand; it should move freely and click. If it sticks or feels loose, replace the switch.
• On models with magnetic reed sensors, ensure the door magnet is still in place and aligned with the sensor.
• Inspect the wiring to the switch for damage or loose connectors; reseat the connector at the control board.
• Test the switch with a multimeter for proper open/closed operation; replace if defective.
• If the switch tests good but E12 persists, the main control board may misread the door input and require replacement.