The sensor is used by the computer for fuel injection timing. As far as a magnet, yes, but I don't see how it would fall off.
If you look at the attached pic, it shows what each wire is used for. Note: Low reference should show continuity to ground. I'm adding them in the event you want to check.
Here is a link you may find helpful:
https://www.2carpros.com/articles/how-to-check-wiring
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Let me know what you find.
Take care,
Joe
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Wednesday, December 9th, 2020 AT 8:45 PM