BMW Werkz banner

Airbag light, passenger seat occupancy sensor

113K views 32 replies 19 participants last post by  caodan2010 
#1 ·
I recently had my seats out of my 97 328i to detail the car and now have my airbag light on. After researching the issue it seems that the passenger seat occupancy sensor pad is the likely culprit as the airbag light appeared when I had turned on the car without the occupancy sensor being connected.
Now that I have reconnected the sensor the light remains. I guess what I am asking is, does a fault due to a missing occupancy sensor require clearing using the srs tool or should it automatically clear if the sensor has been reconnected?

Also, can someone verify that if the passenger seat occupancy sensor is faulty that the result would be both airbags being deployed in and accident whether or not a passenger is present?

Kyle Rogers
 
#2 ·
The fault will not clear on it's own. If you do have the tool or access to one, you can reset it yourself. If the light persists, I suggest taking it to the nearest dealer to have the issue looked into further. An OC3/Seat Mat Sensor is a job you don't want to tackle on your own.
 
#3 ·
The reset will more than likely rectify the problem but there are a couple of alternatives to replacement if the seat occupancy sensor proves defective:-

1. You can take the car to a dealer and have the SRS module reprogrammed to ignore the passenger side seat occupancy sensor and deploy both air bags in the event of a crash, regardless of whether the passenger seat is occupied or not. This process will require a second trip to the dealer for restoration of SRS programming if you later decide to replace the seat occupancy sensor.

2. Go to this free hosted site 4shared - free file sharing and storage - share folder - My 4shared and download instructions (seat occupancy sensor bypass) to make a little circuit so that the SRS module thinks the passenger seat is always occupied (again both airbags will deploy in the event of a crash). The circuit costs around 50 cents to build, does not need a circuit board, fitting will not damage your car and is 100% reversible if you decide to replace the occupancy sensor at a later time.

I have purchased a replacement sensor mat to fit to my vehicle after the original failed, but built the circuit (which has worked flawlessly) so that I didn't have to put up with the warning light until the sensor is replaced.
 
#17 ·
2. Go to this free hosted site 4shared - free file sharing and storage - share folder - My 4shared and download instructions (seat occupancy sensor bypass) to make a little circuit so that the SRS module thinks the passenger seat is always occupied (again both airbags will deploy in the event of a crash). The circuit costs around 50 cents to build, does not need a circuit board, fitting will not damage your car and is 100% reversible if you decide to replace the occupancy sensor at a later time.
I have the same problem with my 520i car and tried to download the file from 4shared.com, but the system is asking for a password "Please enter a password to access this folder:"

Can you please help to get the diagram of this little bypass circuit.


thanks,

panda
 
#4 ·
The fault will not clear on it's own. If you do have the tool or access to one, you can reset it yourself. If the light persists, I suggest taking it to the nearest dealer to have the issue looked into further. An OC3/Seat Mat Sensor is a job you don't want to tackle on your own.
__________________
BMW Technician
Yes the seat mat looks like it would be a big job to install but if it is only the control module it would be an easy job. Will the code reader only indicate that the passenger seat occupancy sensor is at fault or will it go into depth about whether it is caused by the mat or the control module mounted beneath the seat? My guess would be that it will only indicate the occupancy sensor and it will be left to the user to determine which of the mat, control module or both to replace.

Kyle Rogers
 
#5 ·
I have never seen the module go bad. Not saying it doesn't happen, but i haven't seen it. The seat mat sensor is fairly common (on newer vehicles). And as I am not familiar with the scan tool you are using, i cannot attest to how in depth it will go. The thing here is if you do reset it, and it doesn't come back on, you are set. But as I stated before, if it repeats, i do recommend a trip to the dealer. If that is the route you have to go, you will not have to worry about figuring out if it is the module or mat. That will be the responsibility of the dealer.

So if you can come to terms with the fact that you may need to go to the dealer, then the only thing you have to worry about is the bill. I know that sucks, but it's the woes of BMW ownership, or any car for that matter.
 
#6 ·
Thanks for the replies.

I don't have the reset tool but after calling around for a price to have the fault cleared I think I will order the tool and start by simply clearing the fault to see if it comes back on its own. I know that the airbag light came on when I turned on the car without the seats in, so it is likely that just clearing the fault will remedy the problem.

Once again thanks for all the replies.

Kyle Rogers
 
#8 ·
BMW PASSENGER OCCUPANCY MAT SENSOR AIRBAG WARNING LIGHT www.bimtronics.com

I had this problem I was going to replace it but was quoted over £300 because of the labour involved I solved it for £20.00 by buying a Passenger Occupancy Simulator, basically does the job of the sensor without having to spend hundreds of pounds. Well worth the money showed it to a bmw techi and he was impressed. Passenger Occupancy Simulator
 
#14 ·
Disassembly is not difficult - just a time-consuming pain in the butt. You will need to remove the seat from the car and remove the upholstery from the passenger side seat squab - the sensor mat is positioned on top of the seat sqab, between the covering and foam covered base. This is the reason I used the bypass circuit - 10 minutes and $1 in parts vs 3 hours and $200 in parts.
 
#16 · (Edited)
if you are getting CODE 14...(your word) then that means that the supply line to the LF(Left Front) sensor is faulty. That is where you should start probing.

**actually re-check all connectors and clear the light. re-test.

In practice the mat is prone to moisture contamination. ie. passenger spilled cola or juice on the floor and left there... drove through rain/floodwaters... or just came out of the carwash... if that is the case, replacement is the only remedy.

Good Luck
 
#20 ·
I don't know if this will help but does the light go off after a few minutes?

There was a TSB released year ago about the printed circuit board in the buckle of the seat, if it, the wires going into it or the connector it will trigger it.

As long as the light goes off your computer will default to set both airbags off, it it stays on you don't have airbags.
 
#26 · (Edited)
Passenger Occupancy Sensor

Had the same problem. The light is really annoying. The guy at the garage said the airbags will not deploy if it is not fixed which is really worrying when you are trying to concentrate on driving! Followed the link from one of the previous posts BMW Airbag Warning Light Passenger Occupancy Sensor spoke to the Bimtronics Team and got the Simulator.

This is a PROFESSIONALLY made device. I WOULD NOT RECOMMEND MAKING ANYTHING YOURSELF unless you are a qualified professional technician!! It's just not worth the risk!!!

Ask yourself....Would you make your own wheels? No, you would just go out and buy some that were made professionally, otherwise you would be risking your life and your passenger's life!!

BE SMART AND SAFE
 
#27 ·
You have different options other than overpriced dealer's prices to fix the problem. First research, for me google is the way, find a local bmw specialist or a bmw shop. They should have the same computers as the dealer and can fix the same problems for much less.In fact, I got my airbag light cleared in Portland Or place called (German Formula) shop, they specialize in all German cars. they reset airbag for free. it took him 5 minutes at most.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top