Air Bag Warning Light

Z

Zedy

Member
Hello, I am seeking some assistance.

I own a Z4 E85 and have encountered a couple of issues over the last few weeks triggering the red Air Bag Warning light.

Issue 1

The air bag warning light first came on a few weeks ago and on scanning the codes the only code showing was:

Satellite, B Pillar, Right - 991D Battery lead (screen): implausible measured value

If I cleared this code with the scanner the air bag warning light would go out, but comes back on after a short while.

Issue 2

On scanning the car for codes a couple of days ago along with the above code the following new codes (which I have not had before whist checking the issue above over the last few weeks) came up:

Satellite, B Pillar, Left:
9853 Short circuit, firing circuit, front airbag, left, stage 2 (E85), or active head restraint, front right (E6x), to positive
and;
952B Control-unit fault

On seeing these codes I checked the left side of the car and found the carpet and foam underneath were wet behind the passenger seat. I also found some dampness in the boot. I know the boot had definitely not been wet prior to this point but am not sure how long the area behind the passenger seat had been wet.

I have checked the rear drain holes on both sides and they seemed clear as water was draining freely but I cleaned the rubber bungs and the drain holes in case. I have done a water test on the left door, window and roof but showed no leaks from there.

I have taken steps to dry floor behind the passenger seat but due to the weather, it has been difficult to get it completely dry yet.

The floor behind the drivers seat is dry.

So I would be very grateful for any advice from those with more knowledge and experience than me on the following questions:

1. What does the error code 991D Battery lead (screen): implausible measured value (issue 1 above) mean and any advice would be appreciated on what may be the likely cause and how to deal with this?

2. I have assumed that the codes for issue 2 - 9853 short circuit, firing circuit, front airbag, left, stage 2 (E85) and 952B Control-unit fault are as a result of the wet floor behind the passenger seat. If so I would appreciate any advice on how to establish where the short circuit is and how to resolve this, i.e. would it be the wiring itself that runs in this area, the pillar airbag module or the main air bag control unit?

3. Any advice on other possible sources of the leak. I am thinking that it might be that the passenger window has not fully closed when I have put the roof back up. It has done that once before for some unknown reason, where it left the window in the auto drop position with a slight gap. Other than that I can’t see where the water got in so any advice would be helpful.

Apologies for the fairly long post but just wanted to explain as best as I can.

Many thanks
 
Welcome to the forum.
Airbag issues are increasingly common this year it seems.
To take your questions in turn:
1. Beside the battery on the left side is a yellow plug. Check this is secure and has no signs of corrosion. Disconnect the battery, wait 10-15 minutes, then unplug the yellow connector, clean it up and fit it back together. This 'may' resolve that code.
2. Pretty certain that damp has killed the SBSL, the left airbag satellite module. It sits under the carpet at the rear of the sill, behind the seat. You need to lift the carpet and get the part number from it. Simplest way is to put a photo of the label on here and we can then advise which modules are exchangeable with it. Some are getting quite rare, so keep your fingers crossed! A new one needs to be coded with VIN and system time. Depending where you are, I can help, or other members can do it too.
3.Obviously, if the water carries on getting in then replacing the module will not last long. The foam holds loads of water so you need to dry that out. Favourite entry points are spilling forward from the well that the roof motor sits in, or through a damaged door membrane. To check this, open the door with the window up and run a hose along the seal at the bottom of the window. Usually, if the membrane is damaged, you will see water coming through at the bottom of the door card, about 6 inches back from the front corner. The other potential entry point is at the frontr, round the pollen filter housing, if debris is blocking the drains under the scuttle panel. If you can ascvertain whether gthe cafrpet is wet all the way back, or just at gthe rear, this will help narrow down the potential leak points.

So that's a fairly long answer to your fairly long post.
Hopefully it's helpful.
I've been collecting airbag modules and offering a service to help people get over these issues, so let me know that part number and hopefully we can resolve your problem.
 
Thank you so much for your very helpful and quick response. I really appreciate you taking the time to do this.

I will follow your advice for each issue and come back to you. It may take me a couple of days doing this with work commitments but will come back as soon as I can.

Thank you again for your help
 
Just coming back with an update after following the very helpful advice previously received.

Source of leak

The roof drains are clear and drain away well. I water tested the doors and no water appears at the bottom of either door to indicate a problem with the membranes.

However, whilst the carpet itself was dry in the front passenger area, when I looked further the foam underneath the carpet in this area was also wet as well as in the rear. I then focused on the front near the pollen filter as suggested. I poured water into the scuttle panel and found that water is leaking from the top of the scuttle drain (not sure of the correct name for this part) that is located in the engine bay near the bulk head on the passenger side. The water leaks out of the top on the engine bay side but when it does this it is also dripping down the inside of the car and under the carpet. I think this is the source of the problem and may have been leaking for a while.

I can see there is a rubber seal on the top of this part where it is fitted in place and on mine this seal does not appear to be seated properly and this is where the water is coming from. The pipe is actually draining water out as normal at the bottom and I put a rod up to check for blockages and there didn’t seem to be any. See photo below showing how the water leaking from this to better show this.

IMG_4709.jpeg

Has anyone encountered this and if so how do resolve this issue?

I removed the 2 plastic nuts I could see that fix this part in place on the engine bay side but it was still rigidly fixed in place. Can it be removed easily?

SBSL Airbag Module

The part number on the left side pillar air bag module is 65.77-6953009. Is this the number needed to find a replacement that will then need programming?

Battery Lead Fault

I disconnected the battery and cleaned the connector as suggested. The code still comes back after clearing. Could it be the battery itself that is causing this code? i.e. if it’s starting to deteriorate or even the incorrect type.

Again any advice is greatly appreciated
 
Well I can help with the airbag module:
you need to replace yours with like for like, or any of these that say they are exchangeable.
Screenshot 2024-07-18 154141.png
 
I have a couple of 3009s but they are of unknown provenance, so I would not want to send you one untested.
I also have a 2887, 4366, and 0299.

Ideally I would suggest you come to me and we trial fit the 3009s first, with the others as back up. (Long way to Norfolk!)
However, if you can find someone closer to you who can do the coding required then I could post you one.

NB.There is also a 2887 on eBay atm.
https://www.ebay.co.uk/itm/166873285719
 
Thanks for all the information and your help about the air bag module.

If Norfolk wasn’t such a long way from me, I would arrange to come to you as suggested to purchase one of the models and get it programmed. Again very kind of you to offer this.

I have purchased the module that you had seen and provided the link to on eBay. If I find someone closer to me that can correctly do the coding then I will get them to do this once I receive the model. If not I might be arranging a trip to Norfolk at some point to see you!

In the meantime I will be trying to progress with resolving the water leak, as it seems pointless to replace the module without sorting this first…and sort the battery lead error too. I will post an update in due course with progress.

Thanks again for all your help, I really appreciate it.
 
That’s great, Newcastle is not far for me at all. I have ordered a second hand left pillar air bag module, thanks to the help from enuff_zed. Are you able to code replacement pillar air bag modules?
 
Zedy said:
That’s great, Newcastle is not far for me at all. I have ordered a second hand left pillar air bag module, thanks to the help from enuff_zed. Are you able to code replacement pillar air bag modules?
Click to expand...

I can. Drop me a message when you have it and we’ll sort it :)
 
Great. I will message you as suggested.

I have just ordered a new water drain and once fitted I am hoping this will solve the water leak and I can dry the carpet/underneath out. I would like to get this done before the replacement air bag module goes in.

Unfortunately the new water drain may take a week or two to arrive from BMW, but as soon as I get this fitted I will message you.

Thanks for your help, it’s much appreciated
 
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