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.

DTCs P2122, P2123, P2127, P2128, and P2138 are Type C DTCs.
The driver information center, if equipped, may display a message.
The ECM commands reduced engine power as a safety remedial action.
Diesel particulate filter (DPF) regeneration is inhibited.