It looks to me that the fault code is regenerating itself as soon as you clear it because the cause of the problem has yet to have been fixed. I would suggest troubleshooting/ repacing the seat belt tensioner and related circuit and then reset the codes. Chances are the wire connection at the connector (either end of the circuit(s)) is loose. I have had several similar problems on my '94 850 turbo w/ 164000 miles. It just seems as if the connectors just begin to work loose despite the locking clips and tabs. I have even had to go as far as solder a wire to it's crimp pin connector because of 75% of the wire strands being broken in the OEM crimp. Not quite IPC class 2 specification quality here...maybe it is the vibration from 164000 miles :>)

Prospero