AirbagLight suddenly appearing

Just collected my 2004 Z4 2.5i bimmer and on the way home (after about 30 miles driving) the airbag light suddenly appeared and is now permanent. I know there are dozens of similar entries but would be very grateful for some clarification to two questions I have.
1) The various threads mention seat sensors as the main culprit, are there sensors in both seats, doesn't seem normal to have them in drivers side since airbags wouldn't be need if no driver present.
2) Can the passenger side airbags be manually disabled on all models ? The Driver manual refers to a key method to do this plus a disable notification light, but I don't seem to have either, am I missing something here or is my car not so equipped.

I have just ordered the C310+ scan tool from Amazon which seems to be the favourite.

The airbag sensor mat is only on the passenger seat. The passenger seat lock out (key switch) is not on all cars. I believe it is only on the cars that are equipped with the ISOFIX for car seats.

The 310 is a good unit and will tell you which airbag or module is giving you problems.

My friend, it may be as simple as deleting the fault via the scanner. Mine had it happen after I used the stereo for over two hours, when cranking the voltage dipped so much that the airbag module threw a fault. Cleared it almost a year ago, never came back.

Thanks for responses so far. Received my C310+ this afternoon and connected to the ODB socket (noticed it was very difficult to plug in and remove). However, selected the 'Z4' option and then the 'Body' option and then the 'Airbag option'. Fault came up as an 'undervoltage error', I selected 'CLEAR FAULT' which the C310+ acknowledged. But when starting the car same error light again. Sounds as though there is something triggering the fault each time, could it be a connector issue with the seat sensor ?? all suggestions appreciated.

Made further progress with C310+. It seems the undervoltage may have been a red herring, although light came on again this fault did not re-0ccur. The fault that did show up was as listed below on the C310+

SBSR (Satellite B-Pillar, right)
98E9 short circuit, firing circuit, thorax airbag, read right (E85,E60,E61) or knee airbag, front right (E63 E64), to positive.
95AF Control -Unit fault

Can anyone decipher the above details and guide me in the right direction.