Conditions for Setting the DTC

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2012 GMC Yukon XL, 2012 GMC Yukon, 2012 Chevrolet Tahoe, 2012 Chevrolet Suburban, and 2012 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

The fuel tank vacuum is greater than -12 in H2O vacuum for 5 s.
OR
The FTP is less than -2.5 in H2O or more than +5 in for 60 s after a cold start.
After setting the DTC for the first time, 2 L (0.5 gal) of fuel must be consumed before setting the DTC for the second time.