Perhaps these may be of help:
Passenger Airbag Light Stays On and Codes
Help AirBag Light Won't Turn Off!
From the 2nd thread:
"I know this is an old thread. But if you cleared the light and ur airbag light came back on, its becuz the airbags are disabled. When i got my headunit installed the installer knicked my airbag wire, so even my traction control light would not go off.
After the shop ran no codes i took it to nissan, who obviously popped with 3 electrical codes... Would of cost me over $800 to fix, however they deemed it the shops fault so of course the shop fixed it... However noone has the best code reader than nissan
Just my 2 cents"
On a side note, what does the CSC noise sound like on cold starts?