Re: 146ti Air bag light on!!!
There is a common cause - the connectors under the seats. Under each front seat there is a box which contains the connectors for the side airbags &, for the passenger seat, the 'bum sensor'. Slide the box off its mounting & disconnect, clean & replace the connectors, making sure that they are making firm contact - a lot of people have removed the connectors altogether & made a more permanent connection to avoid recurrence of the problem.
You'll still have to get the system reset, as removing the fault doesn't clear the fault code; the diagnostic equipment will, in any case, confirm the cause of the problem as it may, of course, be something other than the underseat connectors.
Go to the right place & getting it rest should cost less than £20. I've had problems with one garage whose diagnostic equipment couldn't communicate with my system - go to a Bosch agent & you'll have no problems.
Where are we going & why am I in this handcart?