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Secondary air system (Vehicles 08.95 >)
Function
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◆ The secondary air system blows air in behind the exhaust valve for approx. 30 seconds (dependent upon coolant temperature, engine loading, engine speed and air flow rate) during a cold start (+5 °C ... +40 °C coolant temperature). This produces an oxygen rich exhaust gas, causes after burning and reduces the heating-up phase of the catalyst.
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◆ Activation is initiated by the Motronic control unit (J220) via the secondary air pump relay (J299) to secondary air inlet valve (N112, change-over valve) and combi-valve.
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◆ In addition to the cold start switch-in phase, the secondary air is switched on during idling and checked via the self-diagnosis (up to max. 80 °C coolant temperature).
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◆ If the readiness code is being generated, the coolant temperature can also be above80°C.
Generating readiness code:
=> Repair group 01, Generating readiness code
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