Theory of Operation
WARNING: This page is about a different car, the 2011 RAM Pickup. However, it is still accessible from the selected car via links, so may be relevant.
This monitor can detect a severe restriction in the Air Filter or the inlet hose to the Airbox. This can cause a reduction in air flow large enough to cause damage to other engine components. This will cause the fault to be set. When this DTC is active, EGR flow is disabled.