How can locate the passenger side airbag sensor on a 2003 325i bmw sensor

Question edited for clarity.
Question moved to model category.

Where Are the F-150 Airbag Sensors Located? - It Still Runs

https://itstillruns.com > f150-airbag-sensors-located-798...
The F-150's airbag sensors are located under the driver and passenger seats and inside the safety belts. The location helps the airbag unit determine when ...

Its not in the bumper. Its under the seat under the carpet.

If its what I think it is, it will be the passenger occupied sensor that activates the passenger airbags when there is a passenger present. So if this is faulty you will get an indication on the dash (red light). Now this can be expensive to fix ( unsow seat, replace sensor blah blah blah) up to 1g. There is a cheeky way to bypass it so the airbags are always activated. Look on youtube for bmw passenger occupancy bypass. Good luck.

The seat pressure sensor. if it's the seat sensor you can find a BMW Airbag Bypass, Seat Occupancy Sensor Mat Emulator on ebay, they are cheap and it works well.

they are incorperated into the entire airbag system not seperate

BEFORE doing any of my suggestions read up about working on the airbag system and DISSCONNECT the vehicle battery and go and have a cuppa while the system discharges. Airbags go off like an explosion and injury could occur.
Moving on: Your fault is most likely a faulty passenger presence seat pad located inside the passenger seat. The pads degrade with age.
It could also be simply a bad connection ot the pre-tensioner module. I've had both faults. Again disconnect the battery as the pretensioner is an explosive charge device.
Get a cheap (tenner on ebay) OBD2 bluetooth diagnostic unit and download a free app such as Torque Lite. You can then interrogate the cars computer using your phone or tablet and read the fault codes. A garage will read them but charge you 30 quid upwards to read them.
Youtube has info about a mod to avoid having to spend over 100 quid for a new seat mat. The Occupancy seat sensor is to prevent the passenger side airbag deploying in an accident if no passenger is present. The mod simply makes it always deploy. Oxidation of contacts in the connectors to any safety device can cause the car to log a fault code and show warning lights. Removal and reconnection of plugs and sockets can cure this poor connection. Again DISCONNECT the battery before working on the vehicle. YOU HAVE BEEN WARNED.
You will then have to reset the fault codes stored before the airbag light will go off. This can be done using your phone or tablet with suitable software.

there is no switch for the passenger airbag. it is activated by a weight sensor in the passenger seat. if it senses over 50 pounds in the passenger seat it will then turn the passenger airbag on

Hello: Sir, There are a total of 5 (five) modules in the Inflatable restraint system, ( airbag) I will list them, their purpose and location:
Sensing & Diagnostic Module, the main module located under the rear of center console, Driver side inflator module located left side driver seat back . driver side inpact sensor located left lower side of center left pillar. steering wheel inflator module under the horn pad in the steering wheel. passenger front side inflator module located under righ side of upper instrument panel . Right front passenger side impact module right side of passenger seat lower back. Rf passenger side impact sensor. lower part of center pillar. The left and right sensors are not modules . Note, Codes B0051 and B0053 require replacement and programming with a scanner. Hope this helps you

Depending on which airbag sensor your after. There are 4 crash sensors on these. 2 in the doors for the side airbags, and the other 2 can be located underneath the bonnet. The sensors respond to the relevant airbag on the same side, i.e nearside sensor = passengers airbag, offside sensor = drivers airbag.

The main SRS control unit can be located underneath the centre console, thought ild add this in case you needed it!

Hope this helps!

you mean passenger airbag sensor.......in the seat