| 摘要 |
<p>When an air-fuel ratio detection performed by detecting an output of a downstream sensor (10), which is a limiting-current type air-fuel ratio sensor arranged at a downstream side of a catalyst (6) in an exhaust passage (4) of an internal combustion engine (2), and calculating an air-fuel ratio at the downstream side of the catalyst (6) in accordance with the output, if the output is within a predetermined range including an output corresponding to a theoretical air-fuel ratio, a relationship between the output and an air-fuel ratio that is calculated by calculation means is shifted more to a rich side relative to a correspondence relationship between an output of an upstream sensor (10), which is a similar sensor to the downstream sensor (10) arranged at an upstream side of the catalyst in the exhaust passage (4) of the engine (2), and an air-fuel ratio.</p> |
