It looks like as if this black area is the back site of the polygon. It emerges when you using the "create polygon" option but instead of clicking anticlockwise clicking clockwise then the polygon will be created with the back facing you. I'm not sure if it is that problem, because I don't now what you did before it was there. But I once had the same problem and that caused it. It could also be that there are two faces overlapping each other. May be you have to move down the one vertex at the corner of this black polygon down and weld it with the one underneath it. Those are my idea but I'm not so long 3D modeling too but may be it helped.

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ok so what i did was select the edge then use insert vertices, becase i dont know any other way to do it.

what i want to do is basily create the "hole" for where the wheel will go, i thought i would accomplish this by relocating vertices.

any help is highly appreciated

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Try using the cut tool to cut the shape into your model.

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[Link to www.3dprevis.com]

Another possibility could be the boolean method to simply "cut out" the wheel arch

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thank u all for ur help, much appreciated but i managed to fix it using cut

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