Secondary air system: Function

During cold starting the secondary air system blows air in behind the exhaust valves. This produces an oxygen rich exhaust gas, causes afterburning and reduces the heating-up phase of the catalytic converter. Activation is performed by the Motronic Engine Control Module J220 via the Secondary Air Injection (AIR) pump relay J299 to the combi-valve.

Checking secondary air system → Secondary air system, checking  .