A fluid sensing system includes a sensing element having a positive temperature coefficient of resistance. The system also includes a switch which is switchable between an open position which prevents current from passing and a closed position which permits current to pass. An inductor is connected electrically in series between the switch electric output and the sensing element and a diode is connected electrically in series between the sensing element and the inductor such that an output of the diode is between the switch and the inductor. A hysteretic controller changes the switch from the open position to the closed position when current passing to the sensing element falls to a lower current threshold and changes the switch from the closed position to the open position when current passing to the sensing element rises to an upper current threshold. A voltmeter measures voltage across the sensing element.