It's deffo an air bag fault, not sure which one though, the lights in the over head cluster go off as normal. Just left with the dash light and the warning on the virtual cockpit! See what they say on Thursday, wouldn't mind but got loads of miles to do this week!
Worth noting that if there is pretty much any fault stored in the ECU pre sense will be deactivated. The first sign of the infamous thermostat failure on the S4 is a warning popping up to say pre sense is faulty. So pre-sense may well be fine its just been deactivated by some other fault.
I’ve managed to resolve this by cleaning the front Radar and connection with Contact Cleaner and a Microfibre cloth. Simple fix, you just need to take the Slam Panel trim cover off first which is easy.