Abstract: An oxygen sensing apparatus for detecting an oxygen concentration of a gas is disclosed. The apparatus includes a first electrochemical cell having an oxygen-ion conductive solid electrolyte body and a reference and a measuring electrode, for producing an electromotive force which corresponds to the oxygen concentration of the gas. A reference-gas chamber formed around the reference electrode is provided with a reference gas by an oxygen pumping action of the first electrochemical cell. The apparatus further includes a second electrochemical cell including a solid electrolyte body and a pair of electrodes, one disposed in a measurement-gas chamber formed around the measuring electrode, and the other exposed in an external space. The measurement-gas chamber is provided with an oxygen gas by an oxygen pumping action of the second electrochemical cell to feed oxygen from the external space into the measurement-gas chamber.

Abstract: Method of compensating an output signal (YA) of a sensor exposed to an exhaust gas produced from an air-fuel mixture, the sensor including an electrochemical sensing cell which produces an electromotive force (Vs) corresponding an oxygen partial pressure in an internal space into which the exhaust gas diffuses with a predetermined resistance, and an oxygen pumping cell to which a pump current (Ip) is applied so as to control the oxygen partial pressure in the internal space such that the electromotive force is held at a constant value. The output signal corresponds to the pump current. The method includes the steps of: converting the analog output signal (YA) into a digital signal (YD) by an analog/digital converter; compensating the analog signal to a first sensitivity compensation, by adjusting an input signal range (FSR) of the analog/digital converter according to a coefficient (KA) which corresponds to a coefficient (KO.sub.2) of sensitivity of the pump current of the sensor to the O.sub.

Abstract: A method of compensating an output of a sensor adapted to determine an air/fuel ratio of an air-fuel mixture, depending upon an oxygen concentration of an exhaust gas produced as a result of combustion of the air-fuel mixture, wherein the sensor includes a sensing element which has at least one electrochemical cell each having an oxygen-conductive solid electrolyte body and at least one pair of electrodes The method includes the steps of detecting at least one parameter selected from the group consisting of a temperature Tc of the sensing element, a pressure Pg of the exhaust gas, and a temperature Tg of the exhaust gas, and adjusting the output y.sub.0 of the sensor, based on the at least one parameter detected, to obtain a compensating output of the sensor.