An apparatus and a method provide an output signal indicative of a speed of rotation and/or a direction of movement of a ferromagnetic object having ferromagnetic features and capable of moving. A variety of signal formats of the output signal are described, each of which have pulses at a rate faster than the ferromagnetic features pass by the magnetic field sensor. The magnetic field sensor includes a plurality of diagnostic circuits that detect a failure of the magnetic field sensor and output a diagnostic signal indicative of the failure. The controller can receive the diagnostic signals and generate a sensor output signal including a failure state to indicate the detected failure.