Conditions for Running the DTC: Notes

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

P0451

DTC P0451 runs only when the engine-off natural vacuum small leak test, P0442, executes.
The number of times this test runs can range from 0-2 per engine-off period. The length of the test can be up to 10 minutes.