Orifice plate meters are a popular for being relatively simple, reliable and inexpensive. Their principles of operation are easily understood. However, traditionally there has been no orifice meter self diagnostic capabilities. In 2008 & 2009 a generic Differential Pressure (DP) meter self diagnostic methodology 1,2 was proposed. In this paper these diagnostic principles are applied to orifice meters and proven with experimental test results. The diagnostic results are presented in a simple graphical form designed for easy use in the field by the meter operator.