I have a 2011 A4 Quattro. I removed the driver side headlight so I could install a new condenser. When removing the headlight I disconnected the cable from the Airbag sensor. I reconnected the cable again and everything is working fine except the Airbag light stays on. I have two questions.

1) Does this light have to be cleared with an OBDII or does it indicate a "real fault"
2) If so could anyone recommend an inexpensive unit that would do this as I don't foresee doing a lot of work on the car. (I would like one that would also work on a Nissan.

Any help is appreciated.