摘要 |
At a time point at which an ignition switch is made OFF and an engine is stopped, an output of a downstream gas sensor is read, thereafter, at a time point at which a predetermined time period has elapsed from stopping the engine, the output of the downstream gas sensor changed by flowing the atmosphere back into an exhaust pipe is read. Thereafter, a change in the output of the downstream gas sensor until the predetermined time period has elapsed from stopping the engine is calculated, the change in the output is compared with an abnormality determinant and when the change in the output is smaller than the abnormality determinant, response of the downstream gas sensor is determined to be abnormal.
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