Action Taken When the DTC Sets

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.

DTC P0299 is a Type A DTC.
A message center or an indicator may display reduced engine power.
The ECM commands reduced engine power.
Diesel particulate filter (DPF) regeneration is inhibited.