Why TF would BMW put the temperature sensor there???!!!???
 

Why TF would BMW put the temperature sensor in the lower radiator hose??? I could give two flying cow pies what the radiator temperature is. I want to know the temperature in the cylinder head!

Rant over.

Well,

If you do a little research before the rant, then you will find out:
1. Sensor in lower rad hose is for aux fan near the front bumper.
2. Sensor in the cylinder head is for the dash gauge.

So, no need to rant...

Thank you. I feel better now.

A water cooling system in circulation will reach equilibrium over time. It doesn't matter where they put it.

It matters where they put the temp sensors where they are.

"In circulation" is the key part of that answer. There are a lot of things that can keep the water from properly circulating - which is when you most need to see what the cylinder head is doing.

And that's where the actual temp sensor is.

Like said that additional temp sensor on radiator outlet is only affecting the electric fan activation. It shows how well the radiator is doing its job. This additional sensor is not even fitted on diesel engines.

I'd like to have a diesel X5