Patent ID: 6978598

Claim:
An apparatus for evaluating a deteriorated state of an exhaust gas purifier disposed in an exhaust passage of an internal combustion engine and including a hydrocarbon adsorbing catalyst having a function to adsorb hydrocarbons in an exhaust gas which flows through said exhaust passage and a function to purify unburned gases in the exhaust gas based on a catalytic action, comprising: a humidity sensor disposed downstream of said hydrocarbon adsorbing catalyst for generating an output depending on a humidity of said exhaust gas, an air-fuel ratio sensor disposed at least downstream of said hydrocarbon adsorbing catalyst for generating an output depending on an air-fuel ratio of said exhaust gas, adsorbing ability evaluating means for evaluating a hydrocarbon adsorbing ability of said hydrocarbon adsorbing catalyst using output data of said humidity sensor, and purifying ability evaluating means for evaluating an unburned gas purifying ability of said hydrocarbon adsorbing catalyst using output data of said air-fuel ratio sensor, wherein the deteriorated state of said exhaust gas purifier is evaluated based on evaluated results from both said adsorbing ability evaluating means and said purifying ability evaluating means.