2003 3BMXV03.0LER, 3BMXV03.0M5R & 3BMXT03.0E5R
WARNING: This page does not describe the selected car, but rather 14 other vehicles, including the 2003 BMW Z8, 2003 BMW Z4, 2003 BMW X5, 2003 BMW M5, and 2003 BMW M3. However, it is still accessible from the selected car via links, so may be relevant.
General Description - At cold start, secondary air pump and valve are switched on for their normal operating function. Secondary air delivered into exhaust gas is causing a lean mixture indicated by output voltage of oxygen sensor. Anytime oxygen sensor indicates a lean mixture within maximum time for monitoring, a counter is incriminated by one, up to a predetermined value. This fixed limit corresponds to minimum amount of secondary air (low flow limit check). See Fig 1.