Hi Wilson, I was able to confirm by using the owner's manual that a key code should exist, though I don't have that code. If need be, I hope that the dealer can still supply it based on the VIN.

As I note in another comment, I'm not sure the key is at fault and am worried about the lock. And so far the problem has not recurred, though as you noted earlier, it's quite likely that it will.

But I could definitely have another key made, though as you note they are pricey things. In the meantime, I hope to find my spare key that was made by the same locksmith, though it was slightly less good than my current key and may make no difference.

I'm also wondering whether there was any other way I could have created the problem -- whether it could've been something I did rather than the lock and key. But that seems unlikely and I'm probably just in denial.

Washing a fairly clean car sounds like a virtuous thing, though apparently it caused trouble. I should wash my car much more often -- I tend to wait until intermittent rain will provide the rinse part.