Conditions for Setting the DTC
WARNING: This page is about a different car, the 2007 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
The PCM detects that the actual measured airflow from the MAF, SCIP, and TP is not within range of the calculated airflow that is derived from the system of models for more than 0.5 second.