Method and apparatus for determining high temperature state of air-fuel ratio sensor

摘要

In an internal combustion engine having an air-fuel ration sensor, a lean-side extreme value of the output of the air-fuel ration sensor is calculated when the air-fuel ratio is lean, and a rich-side extreme value of the output of the air-fuel ratio sensor is calculated when the air-fuel ration is rich, and when both of these extreme values are on the rich side or when the mean value thereof is on the rich side, the air-fuel ratio sensor is determined to be in a high temperature state.