Description of minimum air flow check

WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 2010 BMW M6, 2010 BMW M5, 2009 BMW M6, 2009 BMW M5, and 2008 BMW M6. However, it is still accessible from the selected car via links, so may be relevant.

Once the proper operation of SAFM and the SAP is confirmed in the first two sections of the diagnosis, this check tests the tightness and the minimum airflow of the SAS by the use of the SAFM and the oxygen sensors in the exhaust system. The amount of secondary air flow (SAF) is compared to a secondary airflow model. Once the SAF falls considerably below the model a minimum airflow is detected.

The signals of the oxygen sensors are adjacent compared in order to detect the location of malfunction in the main- or the bank-selective part of the SLS-hosing or Valves. In case one bank is detected much richer than the other, this side can be detected as defective, since it gets less SAF. If the signals are approximately even, the fault is in the main part of the SAS.