Two years after recalling 1 million vehicles because of faulty airbags, and a year after federal regulators questioned whether that fix had worked, Nissan is giving the whole airbag recall thing another shot: recalling 3.7 million vehicles that contain airbags that might not deploy properly in the event of a crash. 

Nissan announced over the weekend that it would recall the vehicles in two separate initiatives, putting to end to an investigation opened by the National Highway Traffic Safety Administration in March 2015.

According to a notice [PDF] posted with NHTSA, the first recall involves 3.2 million vehicles in which the Occupant Classification System (OCS) — which uses sensors to identify an occupant in the passenger seat — may not detect an adult in the passenger seat, resulting in the non-deployment of airbags in the event of a crash.

Nissan notes that a number of circumstances could lead to the incorrect vacant classification, including high vibration at idle when the seat is empty and then becomes occupied, or unusual occupant seating postures.

In all, that issue covers model year 2016-2017 Maxima, model year 2013-2016 Altima, NV200, LEAF and Sentra, model year 2013-2017 Pathfinder, model year 2014-2016 NV200 Taxi, Infiniti QX60 and Q50, model year 2014-2017 Rogue, model year 2015-2016 Murano, Chevrolet City Express and model year 2013 Infiniti JX35 vehicles.

The problem first surfaced in early 2013, when Nissan said it became aware of possible issues with the system. The company was unable to determine if the problem constituted a safety defect, but later recalled 990,000 vehicles in March 2014.

However, regulators received 124 complaints from vehicle owners after their cars were fixed, prompting NHTSA to open an investigation into the issue and proposed fix.

The car company now says it is aware of at least three crashes in which the airbag system did not deploy properly. Those incidents resulted in moderate injuries.

In addition to the 3.2 million vehicles that may not detect an adult passenger, Nissan says that 622,000 model year 2013 to 2016 Sentra vehicles are being recalled because of an issue with the Child Restraint system.

According to a notice [PDF] with NHTSA, the front passenger seat belt bracket may become deformed if it is used to secure a Child Restraint System.

The deformed seat bracket may cause the Occupant Classification System to incorrectly classify the installed child restraint, resulting in the front passenger airbag deploying when it should not.

If the airbag deploys when a child seat is installed in the front passenger area, there could be increased risk of injury in the event of a crash.

Nissan says it will notify owners of all the recalled vehicles and a dealer will make appropriate repairs when parts are available.

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