Conditions for Setting the DTC
WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The ECM detects that the temperature difference between both EGR temperature sensors is not within a calibrated range, for greater than 3 seconds. The difference can be from 1°C to 10°C depending on operating conditions.