The present invention generally pertains to a diagnostic tool for a mobile device such as a smartphone or laptop, which helps a user to control, monitor, diagnose and troubleshoot a movable barrier operator. In an exemplary embodiment, software is downloadable by the user from their phone's service provider, or from an operator manufacturer's website. The software comprises a graphical user interface, which allows a user to execute various diagnostic and monitoring functions. The operator is configured with a network interface for communicating with the mobile device wirelessly. Such an interface may comprise Bluetooth, Wi-Fi, NFC or any other wireless communication available.