CATALYST DIAGNOSIS APPARATUS CONCERNING DOWN-STREAM OXYGEN SENSOR AND DIAGNOSIS METHOD THEREOF

摘要

PURPOSE: A system and device for diagnosing catalyst inactivation is provided to improve a harmful component purifying function in a vehicle system. CONSTITUTION: A system for diagnosing catalyst inactivation comprises next steps. An air cumulative quantity, catalytic temperature modeling value and catalyst diagnosis value are collected after fuel cut-off. It determines that catalytic temperature modeling value and catalyst diagnosis value satisfy the catalytic deactivation diagnosis condition based on based on air cumulative quantity(303). If it satisfies the catalyst inactivation determination condition, it determines catalyst inactivation based on an output value of a rear oxygen sensor(307).