The National Highway Traffic Safety Administration said the automaker had not announced a recall schedule for the cars. The recall involves Carrera and Carrera 4 cars made March 7, 2012, through Nov. 12, 2012, that were outfitted with a standard exhaust system.
The recall does not apply to cars outfitted with a sport model exhaust system, the regulator said.
The exhaust systems in the pending recall may fracture and separate from the rear muffler, the NHTSA said.
Porsche, which has its U.S. headquarters in Atlanta, Ga., will replace rear mufflers free of charge, officials said.
Consumers can call 800-767-7243 for information.