Airbag light

A simple reading of the codes if the light happens to stay on long enough. If not, maybe checking for damage to airbag sensors located in or around the front bumper. Just don't go poking around with a test light or anything around these, though, you could cause the bag to deploy, and that would surely ruin your day. If you can't see anything simple, then it is time to let someone qualified and trained to play around in this neighborhood. Good luck, and happy hunting.