Finally got back to this after the EGR had been removed and checked and subsequently replaced. reset ECU adaptions and road test, been out on the road for 2 days now with no issues to report, thanks to all who replied, seems to be cured, and thanks for the e-mail with the Vauxhall technical bulletin regarding this problem, it seems that even on Tech 2 the code description leaves something to be desired. according to the bulletin the cause of the problem is "incorrect learning of EGR parameters in engine ECU" as has been correctly pointed out the EGR can be regarded as part of the air flow circuit, but its bloody confusing when the code description says air flow sensor circuit.