Theory Of Operation
WARNING: This page is about a different car, the 2020 Jeep Renegade. However, it is still accessible from the selected car via links, so may be relevant.
The Multiair system controls the intake valve opening and closing time for faster catalyst light-off at cold starts. For the 2.4L engine, only early valve closing strategy is applied. The monitor detects any malfunction that will cause the intake valve closing time to be over advanced or over retarded by an amount that prevents the fast catalyst light-off.