Air Injection: Description and Operation

Secondary air system

Function

The secondary air system blows air in behind the exhaust valve for 65 seconds during the cold start (+15° C - +35° C coolant temperature). This produces an oxygen rich exhaust gas, causes after burning and reduces the heating-up phase of the catalyst. Activation occurs from the Motronic control module (J220) via the Secondary Air Injection (AIR) pump relay -J299 to Secondary Air Injection (AIR) valve -N112- and combi-valve. Additionally after each subsequent engine start (up to max. 85° C engine temperature) the secondary air system will, after a 20 second delay, switch in for 5 seconds during idling and will be checked by the On Board Diagnostic (OBD).