A system for determining a temperature of a first portion of an engine, and related circuit, and related method of operation, are disclosed. In one example embodiment, the system includes a wheel having a plurality of magnetic teeth, and an electrical circuit including a variable reluctance sensor (VRS) including at least one winding, the VRS being positioned proximate the wheel, where the VRS is in thermal contact with the first portion, and a comparator having first and second input terminals and an output terminal, where the comparator is configured to output an output signal at the output terminal. Either the output signal or a further signal generated by the electrical circuit is at least indirectly indicative of a resistance of the at least one winding, whereby an indication of the temperature of the first portion can be determined based upon the output signal or further signal.