Help please I own a 03 superb 1.9 diesel 100hp it cut out on wednesday and the plug-in diognastics said speed sensor I have replaced both timing and crank sensors it still will not fire up can any one help me URGENTLEY

Is'nt it still under warranty?

I don't know the answer but it might help if you post full details of any error codes prior to the work you did. Could it have been the relatively common Relay 109 problem in the first instance which caused the engine to cut? Try Search and you will find plenty of references to that particular problem, although it may not affect the Superb.