Toyota Motor Sales U.S.A. has repaired more than 4 million vehicles affected by recalls linked to unintended acceleration.
Toyota Division General Manager Bob Carter said 78 percent of 2.3 million vehicles falling under the "sticky pedal" recall have been repaired. The other recalls from unintended acceleration were attributed to floor mats that got stuck under the accelerator.
Toyota may face more repairs and further government scrutiny.
The automaker plans to recall 90,000 vehicles in Japan on Monday, July 5, to fix engines that may stall while driving.
The world's largest automaker plans a similar action this week for some 137,000 engines in Lexus vehicles in the United States.
The Japan recall affects seven Lexus models and the Toyota Crown, a sedan not sold in the United States, spokesman Paul Nolasco said. The Lexus models include the GS 350, GS 450h, GS 460, IS 350, LS 460, LS 600h and the LS 600h L.
Toyota said a day earlier that faulty valve springs in some V-8 and V-6 engines could trigger abnormal engine noise or idling. In rare cases, they could cause the engine to stop while it is operating. The problem was caused by contamination during the manufacturing process.
Toyota also said last week that it would stop selling the HS 250h after too much gasoline spilled in U.S. government crash tests, posing a fire risk. The company, which paid a record $16.4 million U.S. fine this year for not complying with auto-safety regulations, said in a letter to the National Highway Traffic Safety Administration that about 17,000 2010 HS 250h sedans would be recalled.
Carter said Toyota's "Smart Teams" have addressed 2,500 complaints alleging unintended acceleration, without any incidence found of failure of any electronic system."
Separately, NHTSA head David Strickland told the first meeting of a National Academy of Sciences panel reviewing unintended acceleration: "We must do everything possible to fully understand if there are vulnerabilities in these systems to cause this happening." The phenomenon of unintended acceleration has been reported for "every major automaker," he said.
Meanwhile, two congressmen said Toyota must turn over information about brake-override technology in its older model vehicles and describe the role a consulting firm plays in the investigation of unintended acceleration.
Toyota must submit information about the brakes in cars such as the 2005 Toyota Camry, Rep. Henry Waxman, D-Calif., chairman of the House Energy and Commerce Committee, told the company in a letter sent jointly with Rep. Bart Stupak, D-Mich., chairman of the oversight and investigations panel.
They asked Toyota for information about the work that engineering and research firm Exponent Inc. is performing on unintended acceleration in Toyota vehicles, saying Exponent "has not been fully cooperative with the committee's requests." The lawmakers asked the company to contact the committee by Tuesday, July 6, and to provide the requested documents by July 12.
Mike Michels, a spokesman for Toyota's U.S. operations, said he hadn't seen a copy of the letter and couldn't comment, but he said: "We, of course, will cooperate with requests from the committee."
Bloomberg contributed to this report