I spoke to Vince about this, you DO need to use the VAG COM or the other VW software to bleed the system dry, you will also need to match the pump to your ECU as well, i beleive this is a once only thing.... so I didnt even think about a 2nd hand one. not sure on this tho, just readin me bently manual.... in the end it wasnt my pump at fault, it was a loose diagnostic cable. once corrected, it showed as a sensor fault. Pete