| 摘要 |
In an apparatus and method where the interior of a fuel vapor treatment unit of an internal combustion engine is closed off and pressurized air is supplied, so that the presence of a leak of fuel vapor is diagnosed based on a change condition of the pressure inside the fuel vapor treatment unit, the construction is such that the diagnosis is permitted on the proviso that a condition for close to engine start time is detected. As a result, the influence of heat from the engine after the engine has stopped, and the influence of vibration due to the road surface when the vehicle is travelling and of atmospheric pressure changes due to differences in altitude can be simultaneously avoided, so that erroneous diagnosis due to these influences can be prevented, and fault diagnosis accuracy thus improved.
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