| 摘要 |
A failure diagnosis device for an O2 sensor includes an O2 sensor; a heater driving unit driving a heater heating the O2 sensor; and a diagnosis unit controlling the heater driving unit heating the heater, and diagnosing O2 sensor failure after a given amount of time based on an O2 sensor activation status determination using O2 sensor outputs. The diagnosis unit includes a heater controlling unit controlling the heater driving unit; a time measuring unit measuring time that electric current is supplied to the heater, and time used in determining sensor abnormality; an activation status determining unit determining air/fuel ratio changes from a lean to rich state, or from a rich to lean state based on the O2 sensor output; and a failure determining unit determining sensor abnormality based on outputs from the time measuring unit and the activation status determining unit, thereby diagnosing O2 sensor failure without engine operation.
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