Abstract: Disclosed is a sensor control device for controlling a gas sensor of the type having a sensor element, in which a pair of electrodes are arranged on a solid electrolyte body to cause a concentration detection current between the electrodes, and a heater. The sensor control device includes a temperature detection portion for detecting a temperature value of the solid electrolyte body and a control portion for performing feedback control on a heat generation amount of the heater based on a predetermined feedback condition. The feedback condition is set such that, when an evaluation gas simulating an engine exhaust gas discharged by combustion of a stoichiometric air-fuel ratio mixture is supplied as the gas under measurement at 25° C. while switching a gas flow rate of the evaluation gas between 10 m/s and 60 m/s every 10 seconds, a variation width of the concentration detection current is 1.6 ?A or smaller.

Abstract: A sensor control apparatus (1) calculates the concentration of oxygen using a gas sensor (3) including a sensor element (11) and a heater (12). The sensor control apparatus (1) repeatedly obtains internal resistance data representing an internal resistance value Rpvs of an oxygen-ion-conductive solid electrolyte body (14) and pump current data representing the value of pump current Ip which flows between a pair of pump electrodes (15) and (16) and whose value varies with the concentration of oxygen. The sensor control apparatus (1) corrects the value of the pump current Ip based on the internal resistance value Rpvs, a target internal resistance value, and a derivative value dRpvs/dt calculated based on a plurality of the repeatedly obtained internal resistance values Rpvs.