Conditions for Setting the DTC: P1111
WARNING: This page is about a different car, the 2006 Buick LaCrosse and 2006 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
The control module detects that the IAT sensor parameter is less than -36°C (-33°F) intermittently for more than 100 seconds.