The side airbag will not inflate if the front passenger seat is empty, according to Ford. Rear-seat passengers won't be protected by the airbags.
No crashes or injuries have been linked to the problem, according to Ford.
The recall affects Fiestas from the 2011 through 2013 model years. They were built in Mexico from Nov. 3, 2009 to Sept. 21, 2012.
Ford will notify owners and dealers will reprogram the computer that controls the side air bag so it inflates even if no one is in the front passenger seat. The repair will be done for free. Owner's may contact Ford at (866) 436-7332.
The Associated Press contributed to this report.