P0452 and P0453

WARNING: This page is about a different car, the 2008 Pontiac G5 and 2008 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.

DTC P0452 and P0453 run continuously when the ignition is ON.

P0454

DTC P0454 runs only when the engine-off natural vacuum small leak test, P0442, executes.
This test can run once per engine-off period. The length of the test can be up to 10 minutes.
A refueling event is not detected.