Device for injecting air into an exhaust system fitted with catalytic cleaner for a supercharged Otto engine, in whose intake manifold is incorporated a motor driven air compressor operating with internal compression, giving rise to the supercharging. An air bleeding duct is arranged for adjustable air bleeding from the constriction zone of the air compressor to supply this air as additional air to the catalytic cleaner. This air bleeding duct extends from a point in the constriction zone to a point in the exhaust system upstream from the catalytic cleaner. In an inlet section of the intake manifold, located upstream from the compressor, is installed an electronically controlled device for engine idle control during bleeding of the air via the air bleeding duct.