Patent ID: 7073320

Claim:
A fault detecting apparatus for a gas concentration sensor which has a sensor element including a solid electrolyte body, a plurality of electrodes affixed to the solid electrolyte body, and a gas chamber to which a gas to be measured is introduced and at least one of the electrode is exposed and works to produce an electrical signal between two of the electrodes as a function of an amount of oxygen ions traveling through the solid electrolyte body, comprising: a storage device which stores therein fault detectable conditions in which preselected different types of faults of the gas concentration sensor are allowed to be detected, respectively; and a fault detecting circuit working to detect a selected one of the faults stored in said storage device, when one of the fault detectable conditions is encountered during operation of the gas concentration sensor, said fault detecting circuit initiating detection of a corresponding one of the faults based on an output of the gas concentration sensor.