Patent ID: 8015804

Claim:
A secondary air supply apparatus for an internal combustion engine provided with plural cylinders, which supplies secondary air to a portion upstream of an exhaust gas control device, the apparatus comprising: an air pump which supplies air under pressure; a first air passage through which the air delivered under pressure from the air pump flows; a first opening/closing valve which opens/closes the first air passage; a second air passage one end of which is connected to the first air passage at a portion downstream of the first opening/closing valve, and the other end of which is connected to an exhaust passage leading to a predetermined cylinder among the plural cylinders; a second opening/closing valve which opens/closes the second air passage; a third air passage one end of which is connected to the first air passage at a portion downstream of the first opening/closing valve, and the other end of which is connected to an exhaust passage leading to a cylinder different from the predetermined cylinder to which the exhaust passage connected to the second air passage leads; a third opening/closing valve which opens/closes the third air passage; a pressure detector that performs detection of a pressure in the first air passage, the pressure detector being provided between the air pump and the first opening/closing valve; and a failure determining device that determines whether failure has occurred in the secondary air supply apparatus based on a result of the detection that is performed by the pressure detector while the first opening/closing valve is controlled so as to be opened, the second opening/closing valve and the third opening/closing valve are controlled so as to be closed, and the air pump is controlled so as to be stopped.