What part is this? 1999 Mercedes Benz diesel

This is a diesel car and it is leaking coolant. What part is this? Help it is next to the turbo.

Looks like the coolant temperature sensor to me.

If you are pointing to the thing that looks like an electric motor with coolant hoses attached to one end, it’s an auxiliary [electric] water pump.

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Yes what the finger is pointing to

Thanks for the answer!