Bmw 645ci missing sensor

please high light the area your speaking off

Hope this picture helps. Thanks

And this is the loose connector

That looks like a coolant temp sensor

Thanks for the help, no idea why the person who sold me the car would have removed it. I've been driving it for a week no over heating or warning lights. Ill order the part asap. Thanks again

no problem. It could have popped off as its under pressure from the cooling system

That would make sense and maybe the reason for the white coolant residue on the engine.

Hi, so I found out the whole part needed swapping it was the coolant thermostat with the sensor. Some how the old part had the sensor broken so the lead couldn't plug into it. So I swapped the part and all seemed well, I filled up the coolant and run the engine with the cap off then topped up. Took the car for a drive and within 10 mins noticed the temp gauge getting to the correct temp. This used to take about 30 minutes to get the temp gauge to move! So I thought all was good until I found the coolant bubbling and coming out if the coolant tank at the rim. Stopped the car waited for it to cool down then found that the inside of the coolant cap the seal was broken unsure if this was down to me or b4. I can confirm the new thermostat opened as the pipe running off it was cold whilst running the engine then when the fan kicked in both sides of the pipe either side of the thermostat were now hot. So my question is do you think the coolant tank may have been damaged first or do you think replacing the thermostat and plugging the sensor in is now causing the coolant to get too hot. I've ordered a new coolant tank but worried I replace it all and then it happens again. Any thoughts would be appreciated, thanks