I'm now told it's a bad sensor & it won't be in until Friday. That's not a huge inconvenience b/c they gave me a rental car at their expense, but I do wonder why they didn't have even one sensor in stock. I know they don't take up that much room. I was told they don't keep them in stock because they're such an expensive part. I know they're about $100 but there are many more expensive parts than that. Are the sensors a perishable item that they can't be stocked? Also, living in a major metropolitan area I would think one could be gotten more quickly than 4 days. As long as come the end of the week the thing actually works/is fixed, I'll be happy enough. I suspect that when whoever couldn't diagnose the problem on Monday they had the Xfi mechanic look at it today and that's how they ID'ed the problem. I'm thinking of calling and requesting that the Xfi mechanic do the sensor installation, since a number of ya'll have said that wouldn't necessarily happen otherwise.