The CEO, who has spent her career with GM, also says she first found out about the switch problem in late December and had no knowledge of it before that.
Barra spoke to reporters Tuesday for the first time since the company recalled 1.6 million compact cars to repair the problem. The switch can cause an engine to shut down unexpectedly and cause power steering and air bags to fail.
Barra apologized for the loss of life that occurred. GM has admitted knowing about the problem for at least a decade but failing to recall the cars until last month.