Air Injection: Description and Operation

Secondary Air Injection System Function

During a cold start (+15 °C to +35 °C (+59 °F to +95 °F) coolant temperature), air is blown behind the exhaust valves by the secondary air injection (AIR) system for 65 seconds. This produces an oxygen rich exhaust gas, causing after burning and reduces the heating-up phase of the catalytic converter. Activation occurs from the Engine Control Module (ECM) via Secondary Air Injection (AIR) pump relay (J299) to combination valve. Combination valve opens automatically. In addition, the Secondary Air Injection (AIR) system is switched on with a delay of approximately 20 seconds during idle for 5 seconds after every subsequent engine start (up to max. 80 °C (176 °F) engine temperature) and is checked via On Board Diagnostic (OBD).