Secondary air supplying apparatus for internal combustion engine

A secondary air supply apparatus for an internal combustion engine, the internal combustion engine being provided with a catalytic converter in its exhaust passage, said secondary air supply apparatus comprising:

• a secondary air supplying means for supplying secondary air to the exhaust passage;
• an air-fuel ratio detecting means for detecting air-fuel ratio of gases in the exhaust passage and outputting a signal indicative, of the air-fuel ratio, said air-fuel ratio detecting means being disposed in the exhaust passage downstream of a secondary air supply port of said secondary air supplying means;
• and
• a diagnosis means for diagnosing as to whether secondary air is normally supplied to the exhaust passage, said diagnosing means including an activity decision means for deciding as to whether said air-fuel ratio detecting means is activated when secondary air is supplied to the exhaust passage, and a secondary air supplying means diagnosing means for deciding as to whether secondary air is normally supplied to the exhaust passage on the basis of a signal from said air-fuel ratio detecting means when said activity decision means decides that said air-fuel ratio detecting means is activated.