Good point about the possibility of multiple simultaneous failures.

When researching on the internet, I'm getting contradicting information as to where the gizmo is located. Some of them agree that the one they replaced is the correct one, others say, no, it's under the car. I guess it's hard to research this thing.

I'll give it another day of driving before I make any assumptions. If the CEL goes out, then all is well. If not, I'll look at the code again (it wasn't my scan tool, I'd have to borrow it again to check it) and see if it's still P1166 or something else.

Thanks, all!