| 摘要 |
A method of detecting an abnormality in a system for detecting the concentration of an ingredient contained in exhaust gases emitted from an internal combustion engine, including a sensor for detecting the same concentration, wherein a correction value for the air-fuel ratio of a mixture being supplied to the engine is set in response to an output signal from the sensor, the correction value thus set being applied in detecting the abnormality. A first predetermined value and a second predetermined value smaller than the first predetermined value are set, which both lie within a first range defined by an upper limit value of the correction value and a lower limit value of same that can be assumed when the engine is in normal operating conditions. When the correction value continues to fall outside a second range defined by the first predetermined value and the second predetermined value over a limited period of time, it is determined that the system for detecting the exhaust gas ingredient concentration including the sensor is abnormal.
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