Nissan is recalling 1 million vehicles because a defective Occupant Classification System (OCS) might stop the passenger-side frontal airbags from working.

If that sounds familiar, it’s because they issued the same – albeit smaller – recall last year. But now Nissan admits the problem is more widespread than they anticipated and their previous fix didn’t work.

The OCS is supposed to turn on the airbag when there’s an adult in the front passenger seat. but it’s malfunctioning.

Nissan says a combination of factors could cause the problem, such as high engine vibration at idle when the seat is initially empty and then becomes occupied. Even the posture of the passenger could cause the air bag to deactivate.

The recalled cars include the 2013-2014 Altima, LEAD, Pathfinder, Sentra, the 2013 NV200, plus additional Infiniti vehicles. It is expected to begin in April 2014.

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