The Interlock Door Switch is an OEM part for LG microwaves. It is a safety component located on the door of the microwave designed to prevent the microwave from operating unless the door is securely closed. The interlock door switch works with the microwave's electronic control board to sense when the door is open or closed and allow or disallow operation accordingly. Causes of a bad interlock door switch can include normal wear and tear from repeated opening and closing of the microwave door over time. Symptoms of a bad interlock door switch include: The microwave runs or heats with the door open Error codes or diagnostic messages related to door sensors on the control board The microwave fails to operate even when the door is securely closed This OEM LG part is also compatible with some Sears/Kenmore microwaves.6600W1K001C (AP4650823) replaces 1353253.