Hissing sound like air being released

[likeschevy]

Our 2015 Suburban makes a hissing sound like air pressure being released after a drive and you turn the engine off. Seems to start after about as minute or so after the engine has stopped and only lasts about a minute . Seems to be coming from under the rear near the shocks or that general area. Anybody have an idea what it could be.

[POS VETT]

Leak in the self-levelling dampers and system line?

[likeschevy]

I found the cause it is the auto level system releasing pressure, I just never stayed around the car long enough to ever hear it before.