Toyota faces hundreds of lawsuits over acceleration problems that gained public attention after the deaths of a California highway patrolman and his family, which were reportedly caused by the unintended acceleration of his Toyota-made Lexus.
The faulty acceleration prompted Toyota to recall millions of vehicles, beginning in 2009.
(Read more: Toyota gives Japan workers biggest pay raise in 21 years)
Last year, Toyota received approval on a settlement valued at $1.6 billion to resolve claims from Toyota owners that the value of their cars dropped after the problems came to light. It is also negotiating with hundreds of customers who said they had been injured.
"Toyota has cooperated with the U.S. attorney's office in this matter for more than four years," Toyota spokeswoman Carly Schaffner said on Wednesday. "During that time, we have made fundamental changes to become a more responsive and customer-focused organization, and we are committed to continued improvements."
(Read more: Toyota close to$1 billion deal to settle probe: WSJ)