2003 3BMXV03.0UL2

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 solenoid valve are switched on for their normal (small) mass airflow sensor, which is mounted in air tube between secondary air pump and secondary air filter. Anytime mass airflow sensor indicates fixed minimum or maximum air mass values dependent on engine speed during a defined period, a fault will be detected. Fixed minimum air mass values correspond to minimum amount of secondary air (low flow limit check) produced by a defective pump. Fixed maximum air mass value corresponds to maximum amount of secondary air (high flow limit check) caused by leakage between pump and manifold. In case signal of secondary air mass flow sensor is stuck, a fault will be detected. By measuring a certain oscillation of secondary air mass flow, it can be determined whether secondary air valve is jammed open or blocked. See Figure.