Need help doing all round maintenance

[PlenumBiscuit]

Just ran the car with the lead to the temp sensor disconnected and the fan started after about 15secs. But when I took the lead off the sensor looked almost new. The part the was sticking out had a brass coloured nut on it and was very shiny. Everything else around that area was very dirty. I have seen else where that others have had the ECU burn out where the temp sensor leads connect (I think). Anyone know where to find the ECU(if that's the right thing I'm looking for)

Also just replaced the radiator cap(100kPa), there was a bit of build up on the washer. Possibly could have been some oil.

on the left is the little one, its pointless, only controls the dashboard temp guage

on the right is the ECU coolant temp sensor

which one did u buy

i personally found an issue within the plug that goes into the ECU temp sensor, the female holes had been stretched open, and the pins on the ECU temp sensor werent actually touching the female contacts. i had to pull apart the female plug and bend back into place the female so she was tighter in there

u can buy contact cleaner, and spay all the electrical contacts (inside plugs) which may help too

if it was the radiator cap u may never lose coolant again