Patent ID: 7743759

Claim:
A gas sensor controller for controlling a gas sensor that is provided in an exhaust system of an internal combustion engine and produces current outputs corresponding to a concentration of a detection target substance in exhaust gas by being supplied with voltage and produces voltage outputs corresponding to the concentration of a detection target substance in exhaust gas according to a difference between the concentration of the detection target substance around a first electrode of a pair of electrodes of the gas sensor and the concentration of the detection target substance around a second electrode of the pair of electrodes of the gas sensor, the gas sensor controller comprising: an energization limitation portion that, energizes a heater of the gas sensor while limiting an amount of power supplied to the heater when moisture content is adhering on an inner face of an exhaust passage in the exhaust system and that energizes the heater of the gas sensor without limiting the amount of power supplied to the heater when no moisture content is adhering on the inner face of the exhaust passage in the exhaust system; an output control portion that controls the gas sensor to selectively produce current outputs or voltage outputs; and a specific output obtaining portion that obtains voltage outputs from the gas sensor when the energization limitation portion is energizing the heater while limiting the amount of power supplied to the heater, and obtains current outputs from the gas sensor when the energization limitation portion is energizing the heater without limiting the amount of power supplied to the heater, wherein the output control portion controls the gas sensor to produce voltage outputs when the energization limitation portion is energizing the heater while limiting the amount of power supplied to the heater, and wherein the output control portion controls the gas sensor to produce current outputs when the energization limitation portion is energizing the heater without limiting the amount of power supplied to the heater.