I get the same problem occasionally, it’s becoming more frequent so I’m looking for a permanent fix also. I have a recent Scantool.net ELM327 device, and although I have software which lets it access the auxillary ECUs on my Abarth and Alfa, I don’t know of any software which will let it do the same on the XK (mine only sees the engine and transmission ECUs with the default OBDWiz software).
From what I know (remember) about the system, there are two accelerometers on the bumper beam, a fibre optic crush sensor running along the beam, an ECU located toward the rear of the LH front wheel well and the two airbag modules. I’ve heard some horror stories too - not just from Jag owners, Audi apprently suffer a similar problem with a similar Continental branded system. The only reports I’ve heard of deployments were caused by sudden jolts from pot holes or hitting kerbs, not from faults in the system. The system is required as part of pedestrian safety compliance in some countries; I don’t believe it’s possible to remove the system completely without triggering warning messages, apparently it’s possible to circumvent the actuators with some wiring modifications but this may cause problems if you had an accident, may cancel your insurance etc.
If anyone knows of a software which can read the other ECUs in the system (similar to the FIAT ‘Multi ECU’ software), I’d be keen to know too.