Hi,

My partner has a 63-plate Fiesta Titanium Ecoboost (face-lifted version with larger grill)

Up until about 1pm today, it's been largely issue free, but all of a sudden the car will not lock with the remote fobs unless standing right next to the car. It's not been a gradual reduction in range to indicate a expiring fob battery and the issue has occurred with both fobs simultaneously, which is telling me it's a hardware issue on the car.

Are there any known things to try before I book it into the dealer for the inevitable expensive diagnostic & parts replacement routine?

have you tried new batteries, probably both batteries in remote fobs the same age? 

That's certainly possible, although one key is used a lot more than the other...

I'll try swapping one of the batteries out.

other than battery, the only other component is the the rf reciever but i would have thought it either works or doesnt. located to the right of the interior light assy on top of headlining. 

Ok, strangely the keys are behaving properly this morning (we haven't had a chance to replace the batteries yet).

I'll keep monitoring the issue...