Well, this problem has happened twice to me. Both times it has occured because i had removed my climate control module. This most recent time it has happened to me, i was putting an after market head unit in the vehicle. I am not sure why this happens, i believe it is because the srs system runs in a circuit through the head unit. I brought it back the first time it happened, because i recently had my airbags replaced and didn't know if the fix was defective. They said that it was an erroneous code in the system, and they fixed it at no charge to me. This most recent occurrence, i have left it the way it is because i know that it is not affecting anything, and will get around to fixing it eventually.