Passenger Airbag light

I just bought a 2005 Mustang GT today with less than 3000 miles on the clock and noticed on the journey back home that the airbag light stayed on. According to the manual, this happens when the sensors in the seat, seatbelt buckle or whatever isn't working properly as the airbag disables when a passenger isn't in the seat or something like that.

Anyway, no real Mustang dealers in the UK and it's a private sale so that's it, I'm stuck with it. The Ford manual suggests that a dealer has to look at it. Obviously I'll have to look at it so does anyone know where I should start looking? I'm not sure if this is a generic Ford system or not. I'm pretty sure I haven't seen anything like it on UK cars.

The car hasn't been repaired or anything. I've just found a receipt for a job concerning a faulty seat belt pre-tensioner. I don't know if they fixed it and it's come back but I'm a bit irked that the guy was driving the car so would have seen it. Guess I'll have to bite the bullet on this one.

Well the secret is out. I checked it again this morning and it gives a cycled code of 3 flashes, 4 flashes then it stays on. I went through the stuff that came with the car and found a receipt from a London dealer diagnosing as:

Fault code B2292 Seatbelt Pre-Tensioner. Cleared all codes - left front seat belt pre-tensioner faulty - part of left front seat belt. £51.70

So it could actually affect the deployment of the driver's air bag. I rang the guy who sold it to me to ask if it had been fixed and he said no, the part was £180 plus VAT plus fitting so he didn't get it done.

What is it with people like that? Why the hell did he not think it might be worth a mention when he sold the car to me? Would it not have been better to have it done or is it so much better to inconvenience me to have to take it the other side of the country to be rectified. He's really annoyed me now. Some people are so ....aaargh, words fail me!