Air Injection: Description and Operation

Secondary Air Injection System, Function

The Secondary Air Injection system blows in air behind the exhaust valve for a period of 65 seconds during the cold start (+15°C to +35°C coolant temperature).

This produces an oxygen rich exhaust gas, causes after burning and reduces the catalyst heat-up time.

Activation occurs via the Motronic ECM -J220- via the Secondary Air Injection pump relay -J229- to Secondary Air Injection inlet valve -N112-, (change-over valve) and combi-valve.

Additionally, after each engine start (up to max. 85°C engine temperature) the Secondary Air Injection system will (after a 20 second delay) switch in for 5 seconds during idle and is checked by On Board Diagnostic.