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Passenger occupancy sensor

JSz4

Member
I swapped in some M-sport seats to my E85 3.0i a few years ago and no sensor issues but on a recent track day the airbag warning light appeared on dash. Garage diagnosed Passenger Occupancy Sensor and suggested I order a bypass.

From searching see this is common issue, is an eBay one like this fine or best to buy elsewhere?

https://www.ebay.co.uk/itm/134151617591

Thanks
 
EBay ones are fine never had issues

Make sure you buy the right one as there are 2 types, facelift and pre
 
bigwinn said:
EBay ones are fine never had issues

Make sure you buy the right one as there are 2 types, facelift and pre
That one looks like a prefacelift. But it's not the car that matters, but the seat. What car are they from?
 
enuff_zed said:
bigwinn said:
EBay ones are fine never had issues

Make sure you buy the right one as there are 2 types, facelift and pre
That one looks like a prefacelift. But it's not the car that matters, but the seat. What car are they from?

Ah!! The seat advert read 'BMW Z4 E85 E86 M Sport Black Half Leather Seats 2006', so is it the wrong one?

Thanks
 
JSz4 said:
enuff_zed said:
bigwinn said:
EBay ones are fine never had issues

Make sure you buy the right one as there are 2 types, facelift and pre
That one looks like a prefacelift. But it's not the car that matters, but the seat. What car are they from?

Ah!! The seat advert read 'BMW Z4 E85 E86 M Sport Black Half Leather Seats 2006', so is it the wrong one?

Thanks
I think the easiest way is to look under the seat.
Prefacelift have a small black box that the occupancy sensor plugs into. You remove that plug and fit the emulator you linked to.
Facelift don't have that box so you need either a different emulator, or fit the box from a prefacelift.
 
As you've said you have a 3.0i I'm going to assume you have a pre facelift Z4.

Sometimes when fitting facelift seats the occupancy sensors works. I've refurbished many facelift seats and they have been tested in the same car. Sometimes they work and sometimes they don't, some initially work and then bring an airbag light on after a few hundred miles.

I have bought ebay bypass sensors and some haven't worked. I now buy from 'Mats Emulators' and they have all worked so far.

This is the one you'll need if you have a pre facelift Z4:

https://mat-emulators.co.uk/product...e53-e85-airbag-emulator-passanger-seat-sensor

However you'll also need the little black box from under your old seat, which I assume you'll no longer have.

Screenshot_20250612_144026_eBay.jpg
 
Thanks a lot for the help. Yes I have a 2003 pre-facelift.

Checked under the seat and can see a grey cable from the rear/base of the seat that plugs directly in to the yellow unit. No sign of a black box unfortunately. eBay seat advert said 2006 so fits they're facelift. That's interesting it's so hit and miss, I'd no warning lights for first year it was fitted

I still have the original seats so will have a look, how easy is it to remove the black box? The seats don't have to be taken apart to swap the cable do they? Cheers
 
Easy to remove black box and swap it over to new seat. You need the black box and wire like the photo above.

Once all done you'll have the seat belt chime and light warning on the dash. Either plug in the passenger seat belt if no passenger, buy another seat clip or have the warning coded out.
 
JSz4 said:
I still have the original seats so will have a look, how easy is it to remove the black box? The seats don't have to be taken apart to swap the cable do they? Cheers
Very easy! Even I managed it. :thumbsup:
Unplug the occupancy sensor, then slide the rear black plastic cover off the yellow plug and pop out the connector from there. Make note of where it goes and fit in the same place on the new seat (having removed the existing connector from there).
Tie the existing cable up out of the way.
On the facelift seats I fitted there was a slot in the frame right beside the yellow plug that I was able to fit the black box into.
Then stick the emulator on the socket on the black box and away you go.

However, the car now thinks there is someone in the seat all the time and sets off the seatbelt chime.
1. Plug the belt in, or...
2. Get a spare belt buckle connector and plug that in, or ...
3. Find someone with NCS Expert to tell the SBSL not to check the belt buckle conection any more.
 
Usel said:
enuff_zed said:
[ref]Usel[/ref], there's an echo in here. :rofl:

The echo sounded better, much more information :rofl:

:lol: Thanks a lot both, I'll have a look at the old seats on the weekend and give it a go and order one of the emulators from shop suggested
 
enuff_zed said:
JSz4 said:
I still have the original seats so will have a look, how easy is it to remove the black box? The seats don't have to be taken apart to swap the cable do they? Cheers
Very easy! Even I managed it. :thumbsup:
Unplug the occupancy sensor, then slide the rear black plastic cover off the yellow plug and pop out the connector from there. Make note of where it goes and fit in the same place on the new seat (having removed the existing connector from there).
Tie the existing cable up out of the way.
On the facelift seats I fitted there was a slot in the frame right beside the yellow plug that I was able to fit the black box into.
Then stick the emulator on the socket on the black box and away you go.

However, the car now thinks there is someone in the seat all the time and sets off the seatbelt chime.
1. Plug the belt in, or...
2. Get a spare belt buckle connector and plug that in, or ...
3. Find someone with NCS Expert to tell the SBSL not to check the belt buckle conection any more.


Thanks for the advice, removed the cable and black box from the old seat. Will take it to an independent BMW specialist to get the fault code cleared and sort the seatbelt warning
 
Usel said:
As you've said you have a 3.0i I'm going to assume you have a pre facelift Z4.

Sometimes when fitting facelift seats the occupancy sensors works. I've refurbished many facelift seats and they have been tested in the same car. Sometimes they work and sometimes they don't, some initially work and then bring an airbag light on after a few hundred miles.

I have bought ebay bypass sensors and some haven't worked. I now buy from 'Mats Emulators' and they have all worked so far.

This is the one you'll need if you have a pre facelift Z4:

https://mat-emulators.co.uk/product...e53-e85-airbag-emulator-passanger-seat-sensor

However you'll also need the little black box from under your old seat, which I assume you'll no longer have.

Screenshot_20250612_144026_eBay.jpg


8 years ago the occupancy sensor failed on the old passenger seat so the black box I've removed already has an emulator plugged in, it looks like the one in my eBay link however has two cables from the rear connected to a black cube and branded '=TE'.

Assume these fail with time so worth buying the one you suggested?

Thanks
 
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