A sensing system includes circuitry having a diagnostic interface for a powered sensor. Responsive to sensing signals, the circuitry is operable to produce a DC level that is defined by operating or fault conditions. The fault conditions include an open voltage supply, an open sensor power return signal, open communication signal(s), series resistance in a communication signal, fault resistance to ground on the communication signal and fault resistance to a voltage source on the communication signal. The circuitry includes a fault tolerant interface between a wire harness at an output of the powered sensor and a digital input port of a microprocessor for the purpose of un-ambiguous fault detection when distortion of sensor information occurs or when loss of sensor information occurs, and wherein the microprocessor diagnoses a fault as defined by the DC level of the analog signal monitored at the communication signal input to the microprocessor.