| 摘要 |
PURPOSE:To make it possible to accurately judge the characteristics of an O2-sensor without an erroneous diagnosis, by judging the quality of the O2-sensor on the basis of the ratio of a time during which the detection value of the concn. of the component in the exhaust gas of an internal combustion engine show a reference value or more to a time during which it shows the reference value or less. CONSTITUTION:An O2-sensor 13 subjected to measurement is mounted to the exhaust system of an internal combustion engine for which said sensor 13 is used. A gaseous mixture supply test apparatus 15 adjusts a gaseous mixture with a predetermined air/fuel ratio to supply the same to the engine 1. A response ratio measuring apparatus 16 is connected to the output side of the O2-sensor 13. At this time, as shown by a drawing, a response ratio is the ratio TR/(TR+TL); where first time TR during which the output voltage of the O2-sensor 13 is present in a rich side which is higher than a predetermined reference value Vref and a second time TL during which it is in a lean side which is lower than the predetermined reference value. If this response ratio is within a predetermined range, it is judged that said O2-sensor is a good one and, if out of the range, said sensor is judged to be an inferior one. |
