Conditions for Setting the DTC
WARNING: This page is about a different car, the 2011 GMC Yukon, 2011 Chevrolet Tahoe, and 2011 Cadillac Escalade. However, it is still accessible from the selected car via links, so may be relevant.
P2228
The ECM detects the BARO voltage is less than 2 V for greater than 1 s.
P2229
The ECM detects the BARO voltage is greater than 4.5 V for greater than 1 s.