Secondary Air Injection System, Overview

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.