Nissan is recalling 1 million vehicles because the air bag system software might not be able to tell whether there is a person sitting in the front passenger seat, so the air bag might not inflate in a crash. It's the second passenger air bag recall for some of the vehicles. Last April, 82,038 2013-model vehicles from the same group were recalled because a sensor was improperly manufactured and might prevent the passenger bag from working in a crash. Nissan noted in documents on file with the National Highway Traffic Safety Administration that there have been accidents, but no injuries or deaths were specified.