Nissan is recalling 1 million vehicles because the air bag system software might not be able to tell whether a person is sitting in the front passenger's seat and not inflate the airbag 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 with the National Highway Traffic Safety Administration that there have been accidents, but no injuries or deaths were specified.

According to USA TODAY, the recent action involves what's called the occupant classification system, which judges whether anyone is sitting in the passenger's seat in order to decide whether to inflate the bag there in a crash.

Nissan documents say the system might not work if there is "high engine vibration at idle when the seat is initially empty and then becomes occupied, or unusual occupant seating postures immediately upon being seated."

Dealers will reprogram the system at no charge.

The latest action involves 989,701 Nissan and Infiniti brand vehicles, including some of Nissan's best-sellers:

•2013-2014 Nissan Altima (544,139)
•2013-2014 Leaf electric (29,165)
•2013-2014 Nissan Pathfinder (124,202)
•2013-2014 Nissan Sentra (182,569)
•2013 NV200/Taxi (6,696)
•2013 Infiniti JX35/ 2014 QX60 (63,698)
•2014 Infiniti Q50 (unspecified)

Nissan provided a detailed chronology indicating that it has been investigating reports of the problem since last spring, conducted a recall for a different problem then, but continued to see warranty claims. It renewed investigation after learning of new incidents and determined the latest issue as software requiring a recall.