A sensor device, comprising: a sensor for sensing an amount of a physical quantity, the sensor being adapted for providing a sensor signal formed in response to the sensed amount of the physical quantity; a reference circuit being adapted for providing a first calibrated reference signal calibrated to a threshold amount of the physical quantity; a diagnostic test circuit being adapted for providing multiple diagnostic test signals, each diagnostic test signal representing a pre-determined desired sensor response to a particular amount of the physical quantity; a signal circuit being adapted for providing either the sensor signal or a diagnostic test signal as a signal circuit output; a comparator being adapted for receiving and comparing the signal circuit output with the first calibrated reference signal to form a comparison signal; and a control circuit being adapted: i) for controlling the signal circuit, the diagnostic test circuit, and the reference circuit to receive diagnostic comparison signals corresponding to diagnostic test signals and to produce a sensor device diagnostic signal in response to the diagnostic comparison signals; and ii) for controlling the signal circuit, the diagnostic test circuit, and the reference circuit to receive a sensor comparison signal corresponding to a sensor signal and to produce and output a sensor device sensor signal in response to the sensor comparison signal; and, wherein a) the multiple diagnostic test signals comprise a first diagnostic test signal, wherein the first diagnostic test signal represents an upper specification limit calculated by adding a predefined tolerance to the first calibrated reference signal; b) the multiple diagnostic test signals comprise a second diagnostic test signal, wherein the second diagnostic test signal represents a lower specification limit calculated by subtracting a predefined tolerance from the first calibrated reference signal; and c) the upper and lower specification limits define the diagnostic tolerance of the threshold amount. a sensor for sensing an amount of a physical quantity, the sensor being adapted for providing a sensor signal formed in response to the sensed amount of the physical quantity; a reference circuit being adapted for providing a first calibrated reference signal calibrated to a threshold amount of the physical quantity; a diagnostic test circuit being adapted for providing multiple diagnostic test signals, each diagnostic test signal representing a pre-determined desired sensor response to a particular amount of the physical quantity; a signal circuit being adapted for providing either the sensor signal or a diagnostic test signal as a signal circuit output; a comparator being adapted for receiving and comparing the signal circuit output with the first calibrated reference signal to form a comparison signal; and a control circuit being adapted: i) for controlling the signal circuit, the diagnostic test circuit, and the reference circuit to receive diagnostic comparison signals corresponding to diagnostic test signals and to produce a sensor device diagnostic signal in response to the diagnostic comparison signals; and ii) for controlling the signal circuit, the diagnostic test circuit, and the reference circuit to receive a sensor comparison signal corresponding to a sensor signal and to produce and output a sensor device sensor signal in response to the sensor comparison signal; and, i) for controlling the signal circuit, the diagnostic test circuit, and the reference circuit to receive diagnostic comparison signals corresponding to diagnostic test signals and to produce a sensor device diagnostic signal in response to the diagnostic comparison signals; and ii) for controlling the signal circuit, the diagnostic test circuit, and the reference circuit to receive a sensor comparison signal corresponding to a sensor signal and to produce and output a sensor device sensor signal in response to the sensor comparison signal; and, wherein a) the multiple diagnostic test signals comprise a first diagnostic test signal, wherein the first diagnostic test signal represents an upper specification limit calculated by adding a predefined tolerance to the first calibrated reference signal; b) the multiple diagnostic test signals comprise a second diagnostic test signal, wherein the second diagnostic test signal represents a lower specification limit calculated by subtracting a predefined tolerance from the first calibrated reference signal; and c) the upper and lower specification limits define the diagnostic tolerance of the threshold amount. a) the multiple diagnostic test signals comprise a first diagnostic test signal, wherein the first diagnostic test signal represents an upper specification limit calculated by adding a predefined tolerance to the first calibrated reference signal; b) the multiple diagnostic test signals comprise a second diagnostic test signal, wherein the second diagnostic test signal represents a lower specification limit calculated by subtracting a predefined tolerance from the first calibrated reference signal; and c) the upper and lower specification limits define the diagnostic tolerance of the threshold amount.