DTC P2228: Description
WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
The DTC P2228 Barometric Pressure (BARO) Sensor Circuit diagnostic monitors the BARO sensor output. The BARO sensor and circuitry are located inside of the powertrain control module (PCM). The PCM uses the barometric pressure information in order to compensate for altitude changes. The BARO sensor reading is displayed on a scan tool when the ignition switch is ON and the engine is OFF.