Coolant sensor question

[Yonkers320is]

I had a problem with the auxiliary fan not starting when the temp got a little hot. Like past 3/4, but when switching on the a/c it would start right away.
I tested the relays like you guys said, and the fan worked.

So i bought coolant sensor, but i got two of them. One goes into the radiator, but the other looks like for an older bmw.

Where does that second one go, and does it not use a gasket?

Thanks.https://uploads.tapatalk-cdn.com/20181018/47239d945c77953df056dbd076b45a9a.jpghttps://uploads.tapatalk-cdn.com/20181018/530b528d3a1c363dd938b9259d1d043a.jpg

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[BimmerBreaker]

The second one looks like an E60 radiator fan switch but not 100%, the only #'s on that box go to a useless bavarian autosport listing. But the box says 525, which would mean a M54 even if it was an E39, which would mean a totally different cooling system than yours anyways. So yeah, no matter what the second part is wrong

The first one doesn't quite look like the radiator mounted sensor either and that part # in RealOEM only gives the cylinder head coolant temp sensors for M52/M54 engines (not the early style radiator mounted ones) and the M62 waterpump sensor (which apparently shares a switch with the I6 cylinder head sensors)

The correct radiator fan switch part number is 61318360857 based on what I'm finding...