2007 Sentra correct cabin air filter element is one inch too tall. Stuffing it in causes triangular gaps and compressed places so that the air is not filtered yet constricted in some places. Use scissors to cut a little less than an inch off so it is 6.6"x10.4" .Filter is located behind panel that driver’s right foot touches. Grab bottom corner pull rear edge towards driver door to remove panel. Near gas pedal assembly there is a vertical retainer strip with a loop on the bottom. Release loop & unhook top of retainer strip and you will see the white edge of the filter element. Use a paper clip hook to pull it out. To insert new element past gas pedal assy pinch it 3" from end as if to compress window blinds. This will make a D shape that will start into the hole. A properly fitting element will pop back into shape in slot. Replace covers.