Operation

Function
The secondary air system blows air in behind the exhaust valve for 100 seconds during the cold start (+5°C...+3°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 engine control module -J220- via the secondary air injection pump relay -J299- to the secondary air injection solenoid valve -N112-, change-over valve and combi-valve. Additionally after each subsequent engine start (up to max. 90°C engine temperature) the secondary air system will switch in for 10 seconds during idling and will be checked by the self-diagnosis. The oxygen sensor regulation must then be active.