Conditions for Running 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 engine has been OFF for more than 5 hours.
The ambient temperature is warmer than -7°C (+20°F).
DTC P040F runs once per key cycle within the above enabling conditions.