An internal combustion engine, a method of operating the internal combustion engine, and a controller are disclosed. The method may be implemented in part by the controller and comprises determining a shaft angle of an engine shaft; supplying, to an ion sensor fluidly coupled to a combustion chamber of the engine a low voltage at a beginning of a combustion cycle to generate an ion sensor current and a high voltage during an ionization voltage window based at least in part on the shaft angle, wherein the low voltage is configured to prevent premature ignition of fuel in the combustion chamber and the high voltage exceeds the low voltage and is configured to increase the ion sensor current above a current threshold.