The Ford Fiesta is an excellent subcompact car with good reliability ratings, particularly in the last four years of its life. According to our data, the 2011-2015 model has some issues with the catalytic converter, and 2011-2013 has problems with the power train control module.
From NHTSA data, we can see that almost half of all complaints about the  2011-2015 Fiesta are about the powertrain, particularly about transmission control modules and trouble shifting. Additionally, 2014 and 2015 Ford Fiestas have a recall to repair a potential cylinder head leak, which could lead to significant engine damage if not addressed.