Carried out more tests this morning,removed ecu to find burnt track,repaired it & now its running fine.The other garage said that they had also fitted a new starter motor recently,so probably the circuit had been spiked by a boost start at some point. Does anybody know why two of the data link wires go down to a connector under the centre consul,where one just ends(yellow wire i think)& the other wire(grey & white) connects to a red & white wire which goes back up the same route & follows the other two data link wires to the fuse box & immobiliser.Surely it would be easier to just link the red/white & grey/white wires at the data link connector. Anyway,hope this helps someone else in the future,Regards, Andrew