The occupant classification system (OCS) in many Nissan vehicles is so unreliable for the front passenger seat that you should probably think twice before calling 'shotgun.'

When you first sit in a car’s seat, what do you think about? I’m guessing how soft it is, how much lumbar support it provides, or how close it sits to the dashboard. I doubt you give very little thought to the number of sensors under your tush.

This system of sensors is known as the Occupant Classification System (OCS). I would have gone with butt sensor system (BSS), but maybe that’s why I don’t have a job in marketing. Anyway the OCS is there to detect if an adult or child is sitting in the front seat. Airbags are dangerous to children and need to be turned off, whether a child should ever be in the front seat is a discussion for another day.

Think of the OCS as a sophisticated on / off switch that you don't have to aren’t supposed to have to think about. But that’s not the case for Nissan and Infiniti owners.

How OCS Works

When you park yourself in a seat, a pressure sensor measures your weight. The OCS doesn’t just detect weight, however. It also reads your seat’s position (distance from dash), if your seat belt is on (it always is, right?), and how much tension is on the seat belt.

All this data is passed to an Electronic Control Unit (ECU), which then sends information to the airbag system.

If the seat is empty, has a bag of groceries, or is occupied by a child, you’ll see a yellow, dashboard (or console) light indicating the passenger airbag is disabled.

Side note: it’s normal for all warning lights to come on when first starting the car as part of the start-up process. They usually stay on for 7-seconds, or so.

Once an adult sits down the system is activated, airbags can combine OCS data with split-second information from crash sensors and determine if the airbag should deploy at full speed, partial speed, or not at all. Whatever will keep you safest, statistically.

A Quick Note on Newer OCS Technologies

Even with all that data, the OCS can get it wrong. There are numerous complaints from smaller-than-average adults who say their OCS won’t turn on the airbags when they sit down. And then, of course, the opposite is true with larger-than-average kids – an alarming thought.

To get around this, some modern / fancy cars are experimenting with optical sensors, plus respiration and heartbeat monitors.¹

Airbag Warning Light Always On or Flashing

A common complaint from Nissan and Infiniti owners is their airbag “disabled” warning light is always on, or it flashes on / off as they drive. The sensors simply don’t appear to be working.

And with adults in the front-passenger seat, it’s disheartening to see that airbag off light.

The Recalls

Nissan first issued an OCS recall back in 2013 for 82,000 vehicles. At the time, the automaker said the sensors “may have been manufactured out of specification” and could be permanently suppressed.

A year later, in 2014, Nissan issued a much larger OCS recall for 1 million vehicles. Not only was this an admission that the problem was more widespread than they let on, but they also admitted that the fix for the previous recall never worked.

“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.”

A third recall came in November 2015. Nissan placed the blame elsewhere on the supply chain:

“[the supply chain] caused incorrect occupant classification control unit parts to be installed on vehicles that received the incorrect part after the March 2014 recall was completed. There are also vehicles that were not part of the March recall but received the wrong part from other repairs.”

Vehicles involved in the various recalls

Parts unavailable, fixes not working

Depending on how you look at it, recalls are good news – it means Nissan is acknowledging a safety issue exists and is responsible to find a solution.

However, the problem is the lack of a working solution for millions of owners. To date, owners report they are still waiting for an adequate supply of repair parts and, in some cases, have been told to disconnect the airbag until a part can be secured.

Some have noted the importance of telling your local dealership that the “yellow passenger airbag light is on even when an adult is in the passenger seat.”

Airbag Warning Light Lawsuit

Shortly before the third recall, a lawsuit was filed blaming the automaker for failing to come up with a solution.

The lawsuit, Matthew Senci v. Nissan North America, Inc., said through warranty claims, owner complaints, and the early-2013 recall, it’s clear the automaker has known about these issues since “at least” 2012. Yet, there doesn’t appear to be a solution and the damaged OCS makes the car unsafe and hurts its resale value.