Probably a replacement unit. The yaw sensor for the XWD is not the same as the standard one, but it is the same as some Vauxhalls, which moderates the price, if I can find one.
But I may take the current one out and see if it's fixable. I've seen pictures and it looks as if it's held together with screws. But if it's not fixable, the car will be off the road until a new one arrives. I've only found the part on EU sites so far.