You could wait for further solutions or search the net found this doing google search. There were others similar.
key fob is damaged, button gets stuck, or battery going out.
sensor on the doors/trunk/hood is going bad, and its sending back an open signal (prevents you from locking keys in your car).
electric lock module in doors is going bad, connector loose, or wires getting crimped.
If long time use I'd try new fob battery first.
I know its not supposed to happen but in case you get a fault and locked out of your van first before doing anything OPEN one of the doors windows. My guess from experience of same was the Acuation unit in drivers door one wire loose connection Mondeo early version formerly owned by Fred & Elmer Flintstone .
Bob UK, June 2016
