NEW YORK - Toyota Motor Corp. built its reputation in the U.S. as a maker of safe and dependable vehicles, but the quality of the Japanese automaker's fleet continues to be tarnished by serious safety recalls.

Toyota said Thursday it is recalling 2.3 million vehicles in the U.S. to fix accelerator pedals with mechanical problems that could cause them to become stuck. The announcement comes just months after it recalled 4.2 million vehicles due to gas pedals that could become trapped under floor mats, causing sudden acceleration. That problem was the cause of several crashes, including some fatalities.

Toyota said Thursday's recall is due to potential problems with the gas pedal mechanism that can cause the accelerator to become stuck — regardless of whether the vehicle contains a floor mat. Toyota said in certain rare cases, the gas pedal mechanism wears down, causing the accelerator to become harder to press, slower to return or, in some cases, stuck.

In a letter to federal safety officials dated Thursday, Toyota said the problem appeared to be related to the potential build-up of condensation on sliding surfaces in the accelerator system that helps drivers push down or release the gas pedal.

Toyota spokesman John Hanson said the automaker does not yet have a solution to the latest problem but is working to develop one. Toyota will soon be contacting owners directly about the recall, he said.

The recall affects the 2009-2010 RAV4, the 2009-2010 Corolla, the 2009-2010 Matrix, the 2005-2010 Avalon, the 2007-2010 Camry, the 2010 Highlander, the 2007-2010 Tundra and the 2008-2010 Sequoia. Of these, the Avalon, Camry and Tundra models — encompassing about 1.7 million vehicles — also were included in the previous gas pedal recall. Their accelerator pedals could be at risk both of becoming trapped under floor mats and becoming stuck due to mechanical problems.

Hanson said the company is unaware of any accidents or injuries due to the gas pedal problems associated with Thursday's recall, but could not rule it out for sure. He said the recall "came together very quickly."

He added that all of the vehicles involved in the latest recall contain a gas pedal system that comes from a single supplier. He declined, however, to identify the supplier or say whether Toyota would continue doing business with the supplier.

"Responsibility for this in the end is ours," he said.

The National Highway Traffic Safety Administration said in a statement that the problem is "a serious safety issue and we are pleased Toyota is taking immediate action to address it."

Toyota said drivers in the recalled vehicles whose gas pedals become stuck should firmly apply their brakes, drive the car to a safe location, shut off the engine and contact the nearest Toyota dealer. Drivers who experience the problem should not pump their brakes, Toyota said.

Toyota's last recall, announced in November, was blamed for several crashes, including an accident involving a Lexus that accelerated to more than 120 mph before crashing in San Diego, killing four people. It was the sixth-largest recall ever in the U.S.