In this paper, sensor data pertaining to plasma sputtering is examined. A sensor system monitoring power supply signals and detecting arcs was integrated with manufacturing equipment and data collected. In-situ measurements from the sensors correlate with post-process yield metrology, providing a mechanism for improved process control. Furthermore, from the rich set of data streaming from the sensors various classes of faults can be diagnosed. An error calculation and variable transformation methodology is presented so that classes of faults may be discriminated from one another.