My experience with air bags, not Fiat, (Renault) was that there was a very very slightly loose connection in that case under the seat, I was advised to cut out the push fit connector and solder the wires. Very close inspection revealed no problems at all, but I did as advised and this fixec my problem which never returned. I think air bag lights go off by themselves, much as brake warning lights do, once the fault is fixed. I hope you get to the bottom of the problem. My understanding is that airbags should be properly checked after around 10 years to ensure everything is as it should be. If you have managed 20 years it might be worth at least asking a dealer if checks are needed ad what these might be? Good luck Multi ECU scan (Gendam.com)makes easy work of resetting error messages.
