So they reprogrammed engine ECU (DDE)? That should overwrite any old manipulated software.

A glow plug failure should not turn on check engine light, not even sure with the EGR depending what kind of fault it had.

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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