Any electrical connections related to the airbag system can trigger that light since it does a diagnostic check every time you start the car. In my old Impreza, it was caused by a corroded "clock spring" / roll connector in the steering wheel. A side effect was that my horn didn't work. I think other common points of failure are related to the seats or the front sub sensor.
All airbag wiring is bright yellow. Probably the best thing to do if you really want to fix it is to get someone to pull the code (DTC) for you, which will hopefully tell you where the fault is.