Patent ID: 8721854

Claim:
A control device for an exhaust gas sensor that is to be mounted in an exhaust path of an internal-combustion engine, wherein said exhaust gas sensor is equipped with a sensor element having a function for pumping oxygen in a gas, the control device comprising: a positive voltage applicator that applies a positive voltage to said sensor element; a sensor current detector that detects a sensor current flow through said sensor element; a heater that heats said sensor element; a negative voltage applicator that applies a negative voltage, which is a reversal of said position voltage, to said sensor element; and a microcomputer having control logic that causes the microcomputer to: acquire a sensor current flow prevailing upon application of said positive voltage as a sensor output; heat said sensor element by driving said heater after internal-combustion engine startup; and apply a negative voltage when a temperature of said sensor element reaches a predetermined reaction start temperature within a rune between 300° C. and 350° C. and terminates the application of said negative voltage when the temperature of said sensor element reaches a termination judgment temperature which is previously determined to be lower than the activation temperature of said sensor element within a range between 550° C. and 600° C. as a temperature at which said adsorbable species is completely desorbed, after internal-combustion engine startup said microcomputer applies the negative voltage to said sensor element continuously during an entire time period in which the temperature of said sensor element is in a range of 350 to 550° C., during the initial warm-up process for said sensor element.