LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> BMW >> 2003 >> M3 2D Convertible >> Repair and Diagnosis >> Engine Performance >> System >> Engine Performance - Overview >> Engine Management Systems >> Siemens Engine Management System >> Scope Of Output Functions >> Secondary Air Injection
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Secondary Air Injection

This ECM controlled function remains unchanged from the previous Siemens MS 41.1 system, however there is a hardware change.

The Air Injection Inlet Valve mounts directly to the cylinder head, with a passageway machined through the head. This eliminates the external Air Injection manifold distribution pipes to the exhaust manifolds.

Fig 1: Identifying Secondary Air Injection Valve
G03395982Courtesy of BMW OF NORTH AMERICA, INC.