Please forgive me for posting an old thread, but i wanted to inform you all of my experience with a sagging rear end. While my vehicle was in for service at Nissan, the technician stated that the rear of my vehicle was sagging and it was due to a faulty air ride compressor. Nissan replaced the air ride compressor and re programmed the level height to fix it. The total for that was $965.00. The part was 393.88. The rest was for labor. A symptom that i experienced was that when the vehicle was turned on, i would hear like a motor/compressor trying to work in the rear of the vehicle but nothing happened. It was just a sound for about 10 seconds then it would go away. When the compressor was replaced, that sound at startup went away. The car no longer looks like it's sagging and looks great! I don't know if it's a complicated job or not, but Nissan did it with no problem!