So presumambly 3.0d which had the unit from the factory? Do you have the pre-heating option (536) from the factory or is this feature coded afterwards (using from navscreen or MID)? (Without that option installed Webasto will only work as additional heater while engine is running.) Sounds like the Webasto itself is not running but the interior blower only starts. For example INPA has in addition to fault codes good live data from the Webasto to see what is happening or not.

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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