A system for operating a flame sensing device to obtain readings of increased accuracy without degrading the life of the sensor. There may be levels of a flame requiring a precise measurement. One improvement of accuracy uses higher voltage on the sensor, but this degrades the sensor and thus shortens it life. Further improvement may be achieved by limiting the time that the sensor is operated at a higher voltage. Readings, as if the sensor were operated at a higher voltage, may be inferred from actual readings of the sensor operated at a lower voltage.