Airbag off by design with 100 pound passenger. What to do?
September 17, 2013 2:52 PM   Subscribe

I frequently drive with an adult passenger who weighs about 100 pounds. The car is designed so the Passenger Airbag Off light turns on for a passenger under about 100 pounds, which the car assumes is a child. This isn't a defect. It's definitely by design. I'm concerned about safety with the airbag off. What to do?

Sometimes the light turns off (airbag on) but this is the exception. I'm concerned about driving around with an important safety feature disabled. This isn't something the dealership can or will modify. I think it's a flaw in the vehicle's design, but that's neither here nor there.

Any advice here? My first thought was to add weight, but sitting on a dictionary isn't going to be very comfortable. Hanging something from the bottom of the seat could turn that object into a projectile in an accident. My best idea so far is to hang a seat organizer on the back of the passenger seat and stuff some heavy books into it. I'm not sure if this would work, as it may only be measuring weight on the seat bottom.

Any other ideas on how to solve this one?
posted by cnc to Travel & Transportation (15 answers total) 4 users marked this as a favorite
Best answer: Put some sort of weighted pillow on the passenger seat? It should be comfy and heavy enough to trigger the airbag on switch.
posted by booksherpa at 2:56 PM on September 17, 2013

Best answer: As a 100-pound person who is a frequent passenger in a car with a similar problem, I've found I can usually turn the light off by one of:

a) lifting my feet up and putting all of my weight on my butt (this almost always works)
b) holding my purse/something heavy in my lap (which I can then toss into the backseat)
c) having my husband push down on my thighs/pelvis/sitting area to make me heavier

Generally, I have to do one of these things for 5-10 seconds, at which point the light turns off, and once the light turns off at the beginning of the trip, it stays off for the duration.
posted by brainmouse at 2:57 PM on September 17, 2013

What kind of car do you drive? I believe these are called OCS sensors.

I'm not sure your analysis is correct. If you were to put a 50-pound box in the passenger seat, it's not going to turn the airbag off. Have you tried driving with the passenger with and without the seatbelt on?
posted by phaedon at 2:58 PM on September 17, 2013

Not to put too fine a point on it, but there's a good reason why the airbag shuts off:

The airbag could seriously injure a >100 pound passenger.

If you're that concerned, she should either ride in the back seat or in the front with the airbag deactivated and the seat moved as far back as possible.
posted by Oktober at 3:00 PM on September 17, 2013 [15 favorites]

Seconding that the feature may have been designed with children in mind, but the feature is about the weight of the person sitting in the seat --- age notwithstanding.
posted by zizzle at 3:02 PM on September 17, 2013 [2 favorites]

Nthing the safety concerns. Much better to have them ride in the back.
posted by Chaussette and the Pussy Cats at 3:08 PM on September 17, 2013

Best answer: As a 29 year old full-sized adult woman: do not make me ride in the back when I am going somewhere with my husband. That is ridiculous. And, as a full-sized 100 pound woman, I have actually looked into this, and I am safer with the airbag -- a) 100 pounds is way, way on the outside of any dangers and b) the vast, vast majority of children who were injured by airbags were also not wearing a seatbelt. Wear a seatbelt. This 100-pound woman is safer with the airbag on than off. And is fine in the front seat.
posted by brainmouse at 3:12 PM on September 17, 2013 [7 favorites]

Best answer: Oktober's link talks about a 65 lb passenger.

Some more info here about ways that the passenger-sensing systems can sometimes be fooled eg by passenger posture.

Age, not just weight, also makes a difference according to this link from Edmunds:
A June 2005 study conducted by medical researchers at Oregon Health & Science University concluded that young teens age 13 and 14 were also at risk due to their lack of bone density and muscle mass. Critical changes in body composition occur during puberty, and as a result the study found that older teens age 15 to 18 could benefit from an airbag deploying in a collision.
That article is worth reading more fully, because it explains how the make/model year of your car makes a difference to what the sensor is responding to, and what the airbag behavior will be (partial deployment? total deactivation?).
posted by LobsterMitten at 3:13 PM on September 17, 2013 [3 favorites]

Also, you might check your user manual or online forums for your make/model/year of car. Sometimes there is a way to get the system to turn it on/re-check, such as turning the key to the "lock" position and then re-starting the car.
posted by LobsterMitten at 3:20 PM on September 17, 2013

Is the sensor constantly monitoring the seat weight? My wild guess would be it's just a check while the engine gets started.

If it's just a check for the first 20 seconds or so, then could you just sit in the passenger seat, and then turn the car engine on until the light went off, then get out and go to the drivers seat? Or, when your passenger sits down, could they just push on the roof for a few seconds to add weight to their seat to pass the weight test?
posted by Static Vagabond at 3:21 PM on September 17, 2013

Response by poster: The car is a 2010 Mazda3.

As @Brainmouse mentioned, having the passenger ride in the back is not realistic.

As @LobsterMitten mentioned, my understanding has always been that bone density is the primary issue with airbags being turned off. Again, my understanding it that this is an issue with age, not weight. @Oktober's link is specifically about children under 65 pounds, which doesn't apply here. Does anyone have an actual reference that says weight and not age is not the issue with this?

I believe the system does constantly monitor weight, as it turns on and off periodically (once or twice per trip) with this passenger while driving. It is never an issue with a heavier passenger. However, if it's on it tends to stay on and if it's off it tends to stay off.

There is actually already a discussion elsewhere about the issue with this model, but no one came up with a solution, which is why I asked here.

Appreciate the discussion. Anyone have any other tips for a solution?
posted by cnc at 3:29 PM on September 17, 2013

Best answer: This stackexchange thread has a possible solution at the bottom. There might be a height sensor in the seat back that your passenger isn't tripping.
posted by cromagnon at 4:00 PM on September 17, 2013

Our passenger airbag does this for me, and I always weigh at least 114lbs. (Also, an airbag may have saved my life once, so.)

When it happens in our car, we turn off the dumb thing, I readjust my weight further back into the seat, and we restart the car. So far, this has always worked. Turning off the car sucks, so we check the airbag situation before we leave the driveway.
posted by Coatlicue at 5:06 PM on September 17, 2013

Best answer: According to the manual for the 2010 Mazda3 4-door sedan, your model is equipped with "Advanced front air bags with seat belt-use, passenger-weight and driver’s seat-position sensors". These airbags will deploy with less or no force depending on what the sensors tell them.

From the govt site:

Is it safe for small-stature and elderly adults to be seated in front of an advanced frontal air bag?
Yes. It has generally been found to be safe, and will continue to be safe, for smaller adults and elderly people to be seated in front of an air bag as long as they are properly belted, maintain a proper seating position and move the seat as far back as possible.

I am not sure that I would try to second-guess this system. The deployment scenarios are based on rigorous testing, and statistically, having the airbag off would indicate an aggregate result of better survivability for a front-seat occupant when the sensor indicates the airbag should be off. Keep in mind that a smaller passenger is going to have less kinetic energy due to their smaller mass if they are propelled forward by an accident. Adding their vulnerability with a 100mph+ airbag being propelled backward against them may not actually be making them safer.
posted by dhartung at 6:42 PM on September 17, 2013 [1 favorite]

According to the manual for the 2010 Mazda3 4-door sedan, your model is equipped with "Advanced front air bags with seat belt-use, passenger-weight and driver’s seat-position sensors". These airbags will deploy with less or no force depending on what the sensors tell them.

I was told this about my late model car as well. The sensors can tell your position in the car and make a decision about whether or not to deploy. For example, if you were turned sideways or looking into the backseat and it would be more dangerous for the bag to deploy than not, it wouldn't. The airbags systems in modern cars are much more sophisticated than I had previously realized. Perhaps you could have diagnostics run on your system (if that's possible) to ensure it is operating properly and then let it do its thing.
posted by tamitang at 6:59 PM on September 17, 2013

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