Airbag light is also concerned with the seat belt. If no passenger is sitting on the seat the sensor does nothing. On the other side when some thing goes wrong, it triggers the SRS Airbag Malfunction Light to warn the driver to get the car be checked as soon as possible. As I had advised, please get the car be scanned by a good technician and do as needed. Good Luck.
If the airbag warning light is illuminated, it means a problem has been detected in the system and the airbag system has been disabled. You need a scan tool capable of accessing the air bags codes to begin diagnosing the system. There is an occupational seat sensor in the passenger seat that detects the weight of the person sitting in it, if anyone is. If a person sits in the seat that isn't very heavy, i.e. a child or an infant in a car seat, it will disable the passenger side air bag and turn on the lamp for the passenger side air bag disable (unless you have a mechanical disable that uses your key to turn it off) to let you know it has been deactivated.