Honda Giken Kogyo Kabushiki Kaisha

Norio Inamoto

Takahiro Minowa

A valve indicative of the concentration of an emission component contained in exhaust from an internal combustion engine is outputted by an exhaust concentration sensor arranged in the exhaust system of the engine, and the value is compared with a predetermined reference value, followed by obtaining a ratio of a first time period during which the sensor output value exceeds the predetermined reference value to a second time period during which the sensor output value is less than the reference value. The acceptability of the exhaust concentration sensor is determined based on the obtained ratio. Preferably, the sensor is judged to be of acceptable quality when the ratio lies within a predetermined range and defective when the ratio lies outside the predetermined range.

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Wako, Japan

Norio Inamoto