Both fuel pumps get supply via the same K96 relay. So both pumps are active when ignition is on pos.2 but if there is over half tank of fuel the in tank pump is not actually needed. But if inline fuel pump fails there is not enough supply to HP pump and it will reflect on rail pressure.

https://www.pss-autosoft.net/diagram.../E53_EK96A.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