| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a degradation determination device for performing degradation determination of a catalyst converter and a rear air-fuel-ratio sensor with higher accuracy and preventing incorrect determination thereof from being performed. <P>SOLUTION: The degradation determination device includes a degradation determination means which includes a fuel supply stop means including the catalyst converter for purifying exhaust gas from an internal combustion engine and the rear air-fuel-ratio sensor disposed on the downstream side of the catalyst converter, and stopping fuel supply to the internal combustion engine, a response time measurement means for measuring response time of the rear air-fuel-ratio sensor, and a response time tendency calculation means for checking response time tendency, and which determines a response time from a stop of fuel supply until the rear air-fuel-ration sensor outputs a predetermined output signal under different intake air amount conditions, determines a gradient amount as response time tendency of the rear air-fuel-ratio sensor from a plurality of determined response times, and determines degradation of the catalyst sensor if the determined gradient amount is smaller than a predetermined gradient amount. <P>COPYRIGHT: (C)2013,JPO&INPIT |
