I have a st-line estate and when i unlock the car and start the car up the tailgate pops open,i close it again and sometimes it pops open again before i can pull away,i've tried my spare key thinking i had something stuck in my own key but its the same with that.There's no obstruction near the striker that would cause it to open....possible new switch maybe and would this still be a warranty issue as the car is under 2yrs old?

Could check if there is power being supplied to the tailgate release in ignition. 

Sounds like somerhing shorting over to the boot release circuit.
Used to be a common error on the Mk1 Focus (brittle wire insulation snapping wires and shorting over at the tailgate loom) but shouldn't be happening on such a young vehicle.
May be caused by an earthing problem somewhere.

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number plate lights are also out,will go into Ford dealer on Thursday when i'm off,just watched the video on how to change the module,but i'm not very good at these things and would prob damage something else.

 

Thanks for replying.

Definitely sounds like a wiring fault somewhere.
I'd get the loom checked where it feeds through the rubber conduit between the roof and tailgate.

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