Patent attributes
An oxygen sensor deterioration diagnosis apparatus includes an oxygen sensor provided in an exhaust system of an internal combustion engine, an air-fuel ratio control unit for controlling an air-fuel ratio, an operation state detection unit for detecting an operation state of the internal combustion engine, an inversion period measurement unit for detecting an inversion period of an output signal of the oxygen sensor, an oxygen sensor deterioration diagnosis unit for performing a deterioration judgment by comparing the inversion period with a previously set judgment period, and a deterioration diagnosis inhibiting unit for inhibiting, when the operation state detection unit detects the operation state of the internal combustion engine having an influence on the inversion period, the measurement of the inversion period in a period of time of the detection.
