Conditions for Setting the DTC

WARNING: This page is about a different car, the 2008 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.

The ECM detects that the MAF sensor signal is greater or less than the calculated air flow based on engine load and engine speed.
OR
The ECM detects that the MAF sensor signal is greater or less than the calculated air flow, and The ECM detects a significant error in the long term fuel trim at cruising speed.