NEW YORK (CNNMoney.com) -- The National Highway Traffic Safety Administration is investigating possible steering mechanism problems on some 2011 Hyundai Sonatas.
The investigation is based on two incidents reported by Hyundai itself through the government's "Early Warning Reporting" system, a Hyundai spokesman said.
In one case, a universal joint that helps connect the steering wheel to the front wheels allegedly came loose, resulting in a complete loss of steering control, as reported in a NHTSA document. In the other case, a defective bolt caused loosening, but not total separation, of the universal joint.
There were no crashes or injuries in either case, Hyundai spokesman Jim Trainor said. Both cars were repaired and returned to their owners.
The Department of Transportation's auto safety arm has opened a preliminary investigation into the matter. Hyundai has not yet received a formal request for more information on the two cases, a usual first step in a preliminary investigation like this.
"Of course, we plan to cooperate fully in this investigation," Trainor said.
At the time of the repairs, the NHTSA document says, both of the cars had been driven less than 600 miles. Both vehicles were both manufactured at the same Alabama plant during the same month.
The 2011 Sonata, which is produced at the South Korean automaker's Montgomery, Ala., factory, has been a strong seller. The automaker has already sold about 100,000 of them, Trainor said. This new version of the mid-sized sedan went on sale this spring.