A wellbore pumping unit comprising a main pump, a power source, a controller, and a plurality of sensors is provided. A method of performing a diagnostic check of the unit controller and the plurality of sensors when power is applied to the unit controller. A diagnostic application executing in memory writes a status of the plurality of analog inputs of a plurality of valve position sensors, a status of a plurality of frequency inputs of a plurality of flowmeters, and a plurality of calibration data files that correlate to a plurality of sensors to a diagnostic report file. The status of the sensor inputs and calibration data files can be a pass or a fail. The status of the sensor inputs can be displayed on a human machine interface.