Patent ID: 8775051

Claim:
An apparatus for diagnosing temperature state of a catalyst converter comprising a catalyst for cleaning an emission, and a conductive carrier for carrying the catalyst, the conductive carrier being energized for temperature rise of the catalyst, the conductive carrier having a characteristic in which resistance drops with temperature increase, the apparatus comprising: a first obtaining unit configured to obtain an integral of supply power to the conductive carrier for energization of the conductive carrier from occurrence of a warm-up request to the conductive carrier; a second obtaining unit configured to obtain a predicted value of a parameter indicative of a temperature of the conductive carrier based on a current and a voltage supplied to the conductive carrier; and a diagnosing unit configured to: calculate, based on the integral of the supply power to the conductive carrier, a first threshold used to determine whether the conductive carrier is in temperature nonuniform state; and determine, based on the comparison between the first threshold and the predicted value of the parameter indicative of the temperature of the conductive carrier, whether the conductive carrier is in temperature uniform state or in the temperature nonuniform state due to local heating in the conductive carrier as diagnosis of the temperature state of the conductive carrier.