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Home >> BMW >> 2004 >> 545i Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Management - Overview >> E60 Engine management >> Ms45.1 >> Emissions Management - M54B25 / M54B30 Ultra Low Emission Vehicle II (ULEV II) >> Secondary Air Injection >> Notes

Secondary Air Injection: Notes

Injecting ambient air into the exhaust stream after a cold engine start reduces the warm up time of the catalysts and reduces HC and CO emissions. The ECM controls and monitors the Secondary Air Injection.

An Electric Secondary Air Pump and Air Injection Valve direct fresh air through an internal channel in the cylinder head into the exhaust ports.

The Air Injection Valve is opened by air pressure (from the pump) and is closed by an internal spring.

Fig 1: Identifying Secondary Air Injection Components
G03388696Courtesy of BMW OF NORTH AMERICA, INC.

The secondary air pump is equipped with an additional intake hose (4) to accommodate a secondary air filter with the mini HFM (3). The mini HFM is secured in the secondary air cleaner with two screws.