Conditions for Setting the DTC

WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.

The actual and expected states of the AIR Solenoid Relay Control Circuit, DTC P0412, or the AIR Pump Relay Control Circuit, DTC P0418, do not match.
The condition exists for at least 2 seconds.