A Toyota Motor Corp. executive said Tuesday that the company was aware of problems with gas pedal systems as early as in 2007 but could not spot the exact defect and failed to recall products immediately.

Toyota received consumer complaints in 2007 that the gas pedal in its Tundra pickup sometimes wouldn't return quickly when released, Shinichi Sasaki, Toyota's executive vice president in charge of quality and customer service operations, said at a news conference.

Toyota replaced the material of some parts of the gas pedal system, but it did not find the defect that led Toyota to recall millions of cars earlier this month, he said.

Toyota was ultimately prodded by U.S. regulators late last year to make a swift decision on implementing the recalls.