Air Injection: Description and Operation

Secondary Air System

Function
During a cold start (+15° C to +35° C coolant temperature), the secondary air system blows air behind the exhaust valve for 65 seconds. This enriches the exhaust with oxygen, and starts after-burning, thereby reducing the catalytic converter warm-up phase. Control passes from the engine control unit -J220- across the air injector reaction pump relay -J229- to the secondary air valve (-N112-, switch-over valve) and combination valve. In addition, on every subsequent start of the engine (up to a maximum engine temperature of 85° C), the secondary air system will idle for 5 seconds after a delay of about 20 seconds and the self-diagnosis is run.