In working with a wind tunnel/auto simulation, I have employed a symmetry plane to reduce mesh size and solve time.

When working with CFX Mesh, all cells defining the symmetry plane were automatically created in 2d (i.e. remained in the symm plane), but for whatever reason, in ICEM leveraging tetra meshing per the 'fin config' tutorial, a few cells are generated in 3d- which leads to an error in CFX (requires all cells defining a symm plane to be contained in that plane). Is there some special treatment required in ICEM for a symmetry plane to prevent the generation of 3d cells?

Any thoughts are appreciated, Regards-

Your problem may be caused by a wrong tolerance definition in setting the tetra parameters. You can pick-up the 3D cells and assign them to the volume part. A more general way is to mesh first the surfaces and after the volume starting from the 2D meshes. F

This problem is a known issue and has been covered before. Search the forum for "vector parrallel tolerance symmetry".

Make sure you have points and curves defining hard boundaries on that symmetry plane. If you look at only the LINE types under the Mesh display - if you see holes - that is likely where the problems with mesh are. You can move and/or merge nodes to clean the mesh. If you display the SHELLS on the symmetry plane - you can also move those nodes to the appropriate x/y/or z location defining the symmetry plane.