Toyota has admitted it took "too long" to deal with safety issues which led to the recall of 8.5 million vehicles worldwide.
James Lentz, head of Toyota in the US, said that on one issue, "we failed to promptly analyse and respond" to information provided.
Mr Lentz will face questions from a US congressional committee later over the recall and Toyota's handling of it and will appear before the House Energy and Commerce Committee in Washington at 1100 local time (1600 GMT). Toyota president Akio Toyoda will appear in Congress on Wednesday.
In a prepared statement, he said: "It has taken us too long to come to grips with a rare but serious set of safety issues, despite all of our good faith efforts.
"The problem has also been compounded by poor communications both within our company and with regulators and consumers."
He went on: "In the case of sticking accelerator pedals, we failed to promptly analyse and respond to information emerging from Europe and in the United States.
"We acknowledge these mistakes, we apologise for them and we have learned from them."
Congressional committee chairman Henry Waxman wrote to Mr Lentz on Monday and raised three concerns following a preliminary review of the documents provided by Toyota:
Mr Waxman also wrote to Ray LaHood, Secretary of the Department of Transportation, who will also be questioned.
In the letter, he criticises the National Highway Traffic Safety Administration for "lacking expertise" and said its response to complaints about sudden unintended acceleration appears to have been "seriously deficient".
In Mr LaHood's prepared testimony, he said regulators would continue to investigate "all possible causes" of unintended acceleration.


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