Conditions for Setting the DTC
WARNING: This page is about a different car, the 2007 Hummer H2. However, it is still accessible from the selected car via links, so may be relevant.
If, during the engine-off natural vacuum small leak test, P0442, the powertrain control module (PCM) detects an abrupt FTP signal change, other than a refueling event, this DTC will set.