Air Injection: Description and Operation

Secondary air system
Function
The secondary air system blows air in behind the exhaust valve for 100 seconds during a cold start (+ 5° C to + 33° C coolant temperature). This produces an oxygen rich exhaust gas, causes afterburning and reduces the heating-up phase of the catalyst.
Activation occurs from the Motronic Engine Control Module -J220 - via the Secondary Air Injection (AIR) pump relay -J299- to the Secondary Air Injection (AIR) solenoid valve -N112-, change-over valve and combination valve.
Additionally, after each subsequent engine start (up to max. 96° C engine temperature) the secondary air system will switch in for 10 seconds during idling and will be checked by the On Board Diagnostic (OBD). When this occurs, the Oxygen sensor control must be active.