Conditions for Setting the DTC

WARNING: This page is about a different car, the 2007 GMC Sierra and 2007 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The fuel tank vacuum is greater than 12 inches H2O.
The above condition is present for at least 5 seconds.
The FTP is less than -2.5 inches H2O or more than +5 inches H2O for 60 seconds after a cold start.