Air Injection: Description and Operation

Secondary Air Injection system, function
The Secondary Air Injection system blows in air behind the exhaust valve for 65 seconds during the cold start (+15°C to +35°C Engine Coolant Temperature). This will produce an Oxygen rich exhaust gas, causes after burning and reduces the duration of the catalyst heat-up phase. Activation initiates from the Motronic Engine Control Module J220 via the Secondary Air Injection pump relay J229 to the Secondary Air Injection solenoid valve N112, then to the change-over valve and combi-valve.

Also, after each subsequent engine start (up to an 85°C max. Engine Coolant Temperature), the Secondary Air Injection system will after a 20 second delay, switch in for 5 seconds during idle and is then monitored by the system.