A proximity sensing system, comprising: a proximity probe configured to generate an oscillating magnetic field in response to receipt of an oscillating current via a cable, the proximity probe and the cable forming a resonant circuit possessing a capacitance C 1 in parallel with an inductance Li, wherein the resonant circuit possesses an impedance Z 1 that is a function of C 1 and L 1; a controller in electrical communication with the resonant circuit via the cable and configured to output an initial proximity signal voltage based upon a measured change in the impedance Z 1 resulting from perturbation of the generated magnetic field by a ferromagnetic target positioned at a test position with respect to the proximity probe when a predetermined self-testing impedance Z 2 is not connected to the resonant circuit; and a self-testing subsystem configured to, receive the initial proximity signal voltage, place the predetermined self-testing impedance Z 2 in parallel with the resonant circuit, receive a modified proximity signal voltage, different than the initial proximity signal voltage, output by the controller in response to placement of the self-testing impedance Z 2 in parallel with the resonant circuit and placement of the target at the test position, receive a reference proximity signal voltage representing the modified proximity signal voltage output by the controller in communication with a predetermined cable and a predetermined proximity probe with the target positioned at the test position, determine a voltage difference between the reference proximity signal voltage and the modified proximity signal voltage; and output an incompatibility signal after measuring the voltage difference to be greater than or equal to a threshold amount. a proximity probe configured to generate an oscillating magnetic field in response to receipt of an oscillating current via a cable, the proximity probe and the cable forming a resonant circuit possessing a capacitance C 1 in parallel with an inductance Li, wherein the resonant circuit possesses an impedance Z 1 that is a function of C 1 and L 1; a controller in electrical communication with the resonant circuit via the cable and configured to output an initial proximity signal voltage based upon a measured change in the impedance Z 1 resulting from perturbation of the generated magnetic field by a ferromagnetic target positioned at a test position with respect to the proximity probe when a predetermined self-testing impedance Z 2 is not connected to the resonant circuit; and a self-testing subsystem configured to, receive the initial proximity signal voltage, place the predetermined self-testing impedance Z 2 in parallel with the resonant circuit, receive a modified proximity signal voltage, different than the initial proximity signal voltage, output by the controller in response to placement of the self-testing impedance Z 2 in parallel with the resonant circuit and placement of the target at the test position, receive a reference proximity signal voltage representing the modified proximity signal voltage output by the controller in communication with a predetermined cable and a predetermined proximity probe with the target positioned at the test position, determine a voltage difference between the reference proximity signal voltage and the modified proximity signal voltage; and output an incompatibility signal after measuring the voltage difference to be greater than or equal to a threshold amount. receive the initial proximity signal voltage, place the predetermined self-testing impedance Z 2 in parallel with the resonant circuit, receive a modified proximity signal voltage, different than the initial proximity signal voltage, output by the controller in response to placement of the self-testing impedance Z 2 in parallel with the resonant circuit and placement of the target at the test position, receive a reference proximity signal voltage representing the modified proximity signal voltage output by the controller in communication with a predetermined cable and a predetermined proximity probe with the target positioned at the test position, determine a voltage difference between the reference proximity signal voltage and the modified proximity signal voltage; and output an incompatibility signal after measuring the voltage difference to be greater than or equal to a threshold amount.