It can be difficult getting the black box out, depending on which version you have. Mine was hard up under the inlet manifold, and I was told it may be impossible to remove whithout first removing the manifold. I found there was a plastic lug on top of the box restricting clearance, whose only function was to secure the wiring loom. Cutting this off gave more clearance, and I taped the loom elsewhere.
The box is virtually impossible to clean if choked up.