It's not a sensor. It's a heating coil to "fool" the thermostat opening earlier on high load.

https://www.pss-autosoft.net/diagram...1214_M0KFK.htm

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E39 530dA -02 M-Sport Messing metallic
E53 X5 3.0dA -06 Sport Stratus grey
E70 X5 40d -12 M-Sport Space grey