Mysterious connector in engine bay

[Orthohorizon71]

I accidentaly removed the wire (in the front of the picture) from the connector (thing with the nipple) and need to know what the connector is called and if it is important. (The wire runs from the alternator wiring harness).

Thanks,

Skyler

P.S. I know this isnt the knock sensor haynes says they are in the intake manifold. It is also under the exhaust manifold and near the oil filter on the 3vz-fe

Edited August 6 by Orthohorizon71
Missing information