... just putting the car into reverse usually does the trick. I do not believe there is a setting within the SYNC menu's... I will have a look in the morning ..
just gone though the manual, and other then the gear stick moving into reverse, there is nothing else that can turn on/off the reverse parking sensors. It might be an idea to check if your reversing lights come on... as if they do not, then it's fuse 3 that could have gone in the fuse box of the car, this covers the reverse light, reverse camera, reverse sensors.
At the time of asking for the various 'extras', to be included in the purchase price, your dealer might have asked if you required them [reversing censors], if so, they would have told you that a 'City Pack' would be required at a cost of £200. This gives you an icon on the dash screen when you select reverse, showing an outline of the car with coloured dash lines around the rear to indicate closeness to objects, and also it lowers the sound emitted from the radio, or other music device you have switched on in the car at the time
If you didn't request, or ask for something like that at the time of choosing, then the chances are very slim for having the reversing censors working, irrespective of the cars level i.e. Studio, Zetec, Ecoboost. If you look online in the Sales brochure, I think all the lists are there for all the options you might like in, or fitted to the car
Best way to find out what you have on your car is to take your VIN number, and head over to the following site :FORD ETIS
Once you have entered your VIN number and pressed SEARCH, you will see an information highlight panel on the right side of the screen. At the bottom right of the same screen you will see a a blue arrow in a box facing downwards. click on the arrow and that will then list off all the things you have and all the things you do not have in your car. If you are expecting something that the ETIS site states you do not have, poke your dealer as soon as possible, especially if it's a factory fitted only item...
Also for those of you who are at the factory building stage, when you check in with your dealership, they should be able to provide you the VIN number too. It might not be straight away, but I was able to get my VIN 3 weeks before my car actually arrived. So if they say they dont know, try the following week..