Usually injector seals on these engines, Unfortunately you will need to change injector pipes as well.
More then likely it is your cam phazers these are a trouble spot on these engines
The 2014 Ford Fiesta has an inline 4 engine.
The 2011 Ford Fiesta has an inline 4 engine.
The 2013 Ford Fiesta has an inline 4 engine.
The 2012 Ford Fiesta has an inline 4 engine.
a ford fiesta 1.6
check tension on fan belt(s)
The 2013 Ford Fiesta has a 1.6 L base engine size.
The 2012 Ford Fiesta has a 1.6 L base engine size.
The 2014 Ford Fiesta has a 1.6 L base engine size.
The 2011 Ford Fiesta has a 1.6 L base engine size.
The 2012 Ford Fiesta's engine produces 120 hp @ 6350 rpm.