Conditions for Setting the DTC

WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The ECM has determined that the differential pressure across the DPF is greater than a calibrated threshold, based on a calculated exhaust flow rate and the DPF temperature.
The condition exists for greater than 30 seconds.