not sure if it's the same on these later models but on the earlier ones sometime the plugs under the seat for the seat belt pre-tensioners can come unplugged or disconnected and that would throw the light on..

Failing that only way really is to get it plugged in and read the codes which will (should) tell you exactly what's causing the light..

check the easy, obvious things and then get the codes read before you start chucking money at it

HTH