| 摘要 |
<p>A catalyst degradation detection device, determines whether a three-way catalyst has degraded on the basis of the maximum value of the amount of oxygen stored by the catalyst. When determining whether the three-way catalyst has degraded, the amount of stored oxygen is calculated, and the responsiveness of change in the output signal of an oxygen sensor to oxygen concentration change in catalyst-downstream exhaust is measured. Then, on the basis of the responsiveness of the oxygen sensor which measured the oxygen storage amount, the oxygen storage amount is corrected by reducing the same such that the worsened the measured responsiveness relative to a reference value, the greater the reduction in the oxygen storage amount used in determining whether the three-way catalyst has degraded. The corrected oxygen storage amount used is prevented from deviating from the correct value on the basis of a worsening of the responsiveness of the oxygen sensor.</p> |
