Patent attributes
An ECU controls an A/F sensor that is provided in an exhaust system of an internal combustion engine and produces current outputs corresponding to the concentration of oxygen in exhaust gas by being supplied with voltage and produces voltage outputs corresponding to the concentration of oxygen in exhaust gas according to the difference between the oxygen concentration around one of a pair of electrodes of the A/F sensor and the oxygen concentration around the other electrode. The ECU has: an energization limitation portion that, when moisture content is adhering on an inner face of an exhaust passage near the A/F sensor, energizes a heater of the A/F sensor while limiting the amount of power supplied thereto; and a specific output obtaining portion that obtains voltage outputs from the A/F sensor at least when the energization limitation portion is energizing the heater while limiting the amount of power supplied thereto.
