is there a update for the def system

Call the dealer.

Agree. Have the VIN handy when you do.

Is there anything you want in particular from this update?

What are you looking for? Software update, Special Policy? What issue are having? Most of the Special Policies on 2011 are 10yr or 120K whichever comes first. There are Policies for Reductant Reservoir, NOX Sensors, Indirect fuel Injector. Special Policy is NOT a Recall or Campaign it is a Warranty Extension and is performed only if there is a problem. By calling a dealer with your VIN than can see if there are any open Campaigns (Recall) for your Vehicle. Hope this is helpful