Air Injection: Description and Operation

Secondary Air Injection System

CAUTION: When doing any repair work, especially in the engine compartment, pay attention to the following due to clearance issues:
- Route all the various lines (e.g. for fuel, hydraulics, EVAP canister system, coolant, refrigerant, brake fluid and vacuum lines and hoses) and electrical wiring so that the original positions are restored.
- Ensure sufficient clearance to all moving or hot components.

Function
Air is blown behind the exhaust valves by the Secondary Air Injection (AIR) system during a cold start. This produces an oxygen rich exhaust gas, causes after burning and reduces the heating-up phase of the catalytic converter. Activation occurs from Motronic Engine Control Module (ECM) J220 via Secondary Air Injection (AIR) Pump Relay J299 to Secondary Air Injection (AIR) Solenoid Valve N112 (change-over valve) to the combination valve.