LiftMaster 41C4398A RPM Sensor Board Kit

The LiftMaster 41C4398A RPM Sensor Board Kit is an OEM replacement part for select LiftMaster, Chamberlain, and Sears Craftsman garage door openers that use an external RPM (tachometer) sensor. This optical sensor board monitors motor rotation by reading an encoder/interrupter wheel, sending precise speed and direction feedback to the opener’s control board. Accurate RPM feedback is essential for proper travel control and safety reversal; a failing sensor can cause symptoms such as the opener starting and stopping unexpectedly, reversing without reaching the floor, or showing diagnostics that indicate an RPM fault. Use this kit to restore correct motor feedback and dependable operation on compatible chain- or belt-drive units designed for an external RPM sensor.

Designed for residential openers that incorporate a separate RPM sensor board, the 41C4398A helps the operator regulate motor performance and detect obstructions. Installation typically involves disconnecting power, removing the motor cover, swapping the sensor board, and ensuring the optical gap aligns with the encoder/interrupter wheel before reconnecting the harness and testing travel and force settings per the opener’s service manual. Only install on models specified by the manufacturer as compatible with 41C4398A; it is not intended for platforms that use integrated or Hall-effect feedback systems. For safety, unplug the opener before servicing and follow all LiftMaster service instructions and diagnostics procedures for your model.