Methods and systems are provided for a vehicle comprising, during a first condition comprising when an active grille shutter (AGS) position change over a second interval is less than a threshold position change: stalling an AGS motor for a first interval; calculating a fuel economy change over the first interval; and determining a degradation of an AGS sensor based on the fuel economy change being greater than a threshold fuel economy change over the first interval. In this way, various degradation modes of the AGS including faulty AGS position sensors and a mechanical AGS degradation can be differentiated. Furthermore, in the event of an AGS position sensor degradation, the AGS position can be inferred so that operation of the AGS and the fuel consumption reduction advantages conferred therefrom can be preserved.