The National Highway Traffic Safety Administration says it is investigating steering problems in about 500,000 Ford cars.
The investigation covers 2004 to 2007 Crown Victoria, Grand Marquis and Marauder models.
NHTSA says a heat shield in the car can rust, dislodge and cause the steering shaft to jam. It has received five complaints about the issue and knows of one injury. In that case, the steering froze as a driver entered a highway entrance ramp, causing the car to roll over and cause injuries.
Ford Motor Co. says it will cooperate with the NHTSA on the investigation.