A magnetic flow meter includes a flowtube arranged to receive a flow of process fluid and a coil proximate the flowtube arranged to apply a magnetic field to the process fluid. A sense electrode is arranged to sense a voltage potential in the flowtube in response to the applied magnetic field. The sensed voltage is indicative of flow rate of process fluid through the flowtube. Diagnostic circuitry provides an output related to an electrical path between the coil and electrical ground.