Bit of a long shot but i have a knocking on my Fiorino and I wondered if anyone has had a similar problem.It sounds like its coming from behind the dash behind the clocks but maybe the noise is travelling up from5the outside? Took it to the garage and thought we had found it because one of the brake caliper bolts was loose,but after tightening it up the knock was still there. He checked everything while it was on the ramp but everthing was good.