Secondary air supply system and abnormality detection method for secondary air supply system

摘要

During secondary air supply control, a secondary air supply system which supplies secondary air to an upstream side of an exhaust gas control apparatus obtains a secondary air flow rate supplied to an exhaust passage provided independently for each of a plurality of cylinder groups, and detects an abnormality in the secondary air supply system based on a noxious substance amount in exhaust gas discharged from the exhaust passages which is determined from the obtained secondary air flow rates.