Conditions for Running the DTC

WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

P0451

Before the PCM can report DTC P0451 failed, DTCs P0443, P0452, and P0453 must run and pass.
The engine is running.
The ambient air temperature is greater than 4°C (40°F).
The vehicle speed is greater than 45 km/h (28 mph).
The FTP sensor voltage is greater than 0.3 volt.
The purge flow fluctuation is greater than 0.05 kg/h.
DTC P0451 runs continuously once the above conditions are met.

P0454

The ignition is ON.
The ignition voltage is between 9-16 volts.
DTC P0454 runs continuously once the above conditions are met.