The LiftMaster 41D7924-1 MyQ Extra Sensor is the add-on wireless door-position sensor designed specifically for the LiftMaster 821LM MyQ Garage controller. Used as a replacement part or to expand an existing 821LM setup, this sensor lets the MyQ system monitor and control an additional garage door through the MyQ app. Once installed on the top panel of the door, the sensor detects door movement and open/close status and communicates that information to the 821LM hub, enabling reliable status updates, notifications, and app-based operation when used with a compatible opener.
This accessory is intended for residential sectional garage doors and requires a functioning LiftMaster 821LM hub; it does not operate as a standalone device and is not intended for newer Smart Garage Hub models. One sensor is needed per door. Installation is straightforward: mount the sensor on the door as directed by LiftMaster, then place the 821LM in learning mode to pair and name the new door in the MyQ app. For best results, mount away from hinges or obstructions, and verify safe door operation and reversal systems after setup. This genuine LiftMaster MyQ door sensor is a dependable way to add a second door to an 821LM system or replace a worn sensor while maintaining full MyQ compatibility and smartphone control.