A lift device includes a chassis, a platform configured to support a user, a lift assembly coupling the platform to the chassis, an actuator configured to at least one of (a) move the platform relative to the chassis or (b) propel the chassis, a sensor assembly, and a controller. The sensor assembly includes a rod including a first end portion coupled to the platform and a second end portion opposite the first end portion, a housing defining an aperture sized to receive the second end portion of the rod, and a sensor coupled to the housing and configured to provide a signal in response to the second end portion of the rod exiting the aperture. The controller is operatively coupled to the sensor and the actuator and configured to control the actuator in response to receiving the signal from the sensor.