I wasn't entirely sure myself, but a member here has quoted it to be a mileage counter only:
http://www.ecodieselram.com/forum/threads/ecodiesel-oil-change-intervals.35/#post-4010
You can have the EGR disabled inside the engine computer with tuning. However, remember any kind of tuning *CAN* void your warranty if any serious problem comes up and the dealer snoops around in the ECM.
The EGR is part of the emissions system on the EcoDiesel (actually any modern diesel...
Go here: http://www.dodge.com/webselfservice/dodge/index.html
Click the link on the left corner called "Equipment Listing", then input your VIN #. That should show what ratio you have.