Toyota Funcargo (Yaris Verso) 1.3 VVTi (2NZ-FE) connector near oil filter

That looks like the oil pressure sensor wire and plug. The weird thing is that I don't see the connection on the block behind it. You might look around and see if you can find a plug similar to the one shown in this image. It should be above/after the oil filter, because it's detecting the pressure of the oil being pumped through the filter.

You should also check for a broken plug which is screwed into the block but has the plastic plug part broken off of it. After a few years, those plastic clips often become brittle, especially when exposed to heat, and can be easily broken. If that's the case you'll probably need to buy a new oil pressure sensor, or figure out a hack job to connect the wire to the broken one.