ambient air temp.sensor
 

when I bought my ml I noticed that on the cluster it does not show the outside temp.I looked in the owners manual and it says that it is optional.So I figured that who ever had this car first did not get that option.I looked in the fron bumper and found the plug without the sensor in it,so I picked one up at the dealer and put it in but it still does not show up on the cluster.
is this something that has to be activated by the dealer?Any help would be greatly appreciated.