What is this sensor for?

[ViPeR_NiPPleX]

it's a single wire, which is typically a guage sensor ie. water temp / oil pressure

ecu water temp is normally green, and cold start is brown... unless its a newer toyota motor and they've changed sensors

[JetspeedCamry]

it's a single wire, which is typically a guage sensor ie. water temp / oil pressure

ecu water temp is normally green, and cold start is brown... unless its a newer toyota motor and they've changed sensors

Yep thats it, and that leaves 2 more sensors on the upper and lower radiator housings. One is said to be a thermo fan switch, so the other is!?? So far we have Climate Control sensor and transmission ECU sensor.

[AndyTTR]

Is that sensor screwed into the head? It looks like its near your injectors? Maybe its an oil pressure switch? Doesn't look to be the right shape to be oil pressure tho.

My car of a similar vintage had;
- thermofan switch in the thermostat housing (which has the same plug as your 3rd pic),
- cold start injector switch, ECU temp sensor and temp gauge sender in the coolant outlet from the head. My temperature gauge sender had a single blue plug too.

[Robbos_Toyotas]

the one with the spade bit connectore on it is the temp gauge sensor. nothing else