The automaker formally informed the federal government of the recall in a letter Monday. It will be Toyota's largest U.S. recall and the country's sixth-largest recall, according to the National Highway Traffic Safety Administration.
The recall includes 2007-2010 model year Toyota Camry, 2005-2010 Toyota Avalon, 2004-2009 Toyota Prius, 2005-2010 Tacoma, 2007-2010 Toyota Tundra, 2007-2010 Lexus ES350 and 2006-2010 Lexus IS250/IS350.
Chris Santucci, Toyota's assistant manager for technical and regulatory affairs, wrote in the letter to NHTSA that there are 3.8 million vehicles involved but "this estimate is subject to change as Toyota refines the number of affected vehicles by model."
Toyota told the government it has not determined that the vehicles "contain a 'safety-related defect' within the meaning of the federal safety laws" but would notify owners of the safety campaign.
Santucci wrote "there is a potential for an accelerator pedal to get stuck in the wide open position due to an unsecured or incompatible driver's floor mat. A stuck open accelerator pedal may result in very high vehicle speeds and make it difficult to stop the vehicle, which could cause a crash, serious injury or death."
Toyota announced last week it would recall the vehicles and warned owners to remove the driver's side floor mats and not replace them until the company determined a way to fix the problem.
The massive recall was prompted by a high-speed crash in August involving a 2009 Lexus ES350. California Highway Patrol Officer Mark Saylor, 45, and three members of his family were killed when their vehicle hit speeds exceeding 120 mph, struck a sport utility vehicle, launched off an embankment, rolled several times and burst into flames.
Family members made a frantic 911 call from the Lexus and said the accelerator was stuck and they couldn't stop the vehicle.
In Japan, Toyota President Akio Toyoda said last week that the fatal crash was "extremely regrettable" and offered his "deepest condolences."
Toyota said in the letter it would tell owners of the affected vehicles to take out the driver's floor mat and not replace it with another floor mat until model-specific remedies are developed. Toyota said it expects to begin notifying customers by first class mail in late October and complete its mailing in December.
When it figures out a fix for the problem, Toyota will notify owners "about the availability of a free remedy." The automaker told the government it did not have a firm schedule for the second notification but would provide the government a schedule as soon as possible.
If a vehicle accelerator pedal becomes caught on the floor mat, Toyota recommends the following steps:
— Reach down and pull the mat back from the accelerator. Then pull over and stop your vehicle. If you can't dislodge the pedal or it seems unsafe to do so, press on the brake with both feet. Then shift the vehicle into neutral, which will disengage the transmission. Continue braking until you come to a stop.
A driver can also try shutting off the engine or turning the key to the "ACC" position on the ignition. You won't lose control of steering or the brakes. But once the vehicle is turned off the driver won't have the benefit of power brakes or power steering.