Conditions for Setting the DTC: P2228
WARNING: This page is about a different car, the 2009 Pontiac Torrent and 2009 Chevrolet Equinox. However, it is still accessible from the selected car via links, so may be relevant.
The ECM detects that the BARO sensor voltage is less than 0.20 volt for greater than 1 second or for a cumulative of 10 seconds.