General Motors Co. is recalling more than 47,000 Cadillac SRX crossover vehicles in the U.S. because of a problem with the passenger side air bags.

The National Highway Traffic Safety Administration, in documents posted on its website Friday, said that the right side head protection air bag won't inflate in a crash if no one is in the front seat.

As a result, a right-side passenger in the back seat may not be protected and could get hurt in a front or side crash, the agency said in the documents. GM said no injuries have been reported.

Air bag sensors in the 2011 SRX, an SUV-like vehicle that's more nimble and efficient because it's built on car underpinnings, are programmed to turn off the passenger side air bags if no one is in the right-front seat, the agency said. But that conflicts with the owner's manual, which says the air bags will inflate regardless whether the front seat is occupied.