Ford Motor Co said about 500,000 of its vehicles were being investigated by the National Highway Traffic Safety Administration for steering problems, reported Reuters.
The vehicles include Ford's Crown Victoria, Grand Marquis and Marauder from model years 2004 to 2007, a statement on the NHTSA website said.
The NHTSA is investigating an issue related to a heat shield in Ford cars that can rust, dislodge and cause the steering to jam.
The safety regulator said it had received five complaints and was aware of one injury related to the problem.
The company will cooperate with the NHTSA investigation, Ford spokeswoman Kelli Felker told Reuters in an email.
Earlier in the day, Chrysler Group LLC said it would recall about 900,000 sport utility vehicles (SUVs), its largest recall this year.