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Home >> Volkswagen >> 2004 >> GTI Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> 1.8L - Exhaust System, Emission Controls - AWD, AWP, AWW Generic (A4 Platform) >> Exhaust System, Emission Controls >> Secondary Air Injection (AIR) System >> Function
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Secondary Air Injection (AIR) System: Function

Air is blown behind the exhaust valves by the Secondary Air Injection (AIR) system during a cold start. This adds oxygen to the exhaust, initiating a secondary combustion and thereby shortening the warm -up phase of the catalytic converter. Activation occurs from Motronic Engine Control Module (ECM) -J220- via Secondary Air Injection (AIR) Pump Relay -J299- to Secondary Air Injection (AIR) Solenoid Valve - N112- to the combination valve.

Check secondary air system for proper seal, see CHECKING SECONDARY AIR SYSTEM FOR PROPER SEAL .