Try this for size have recently had problems with transplanting engines in T4 . After swapping engines over I found that the van we put the old diesel engine into would not start . Jmac said to change immobilizer unit as the transponder was coded to the old engine and electrics . Jmac was right but then found that we needed to have the key reprogrammed , he suggested VW dealer asked them for quote approx $85 and book car in lots of time taking van in blah blah . On way home called in to the Logan Hyperdome with keys on the off chance MR Minit might have the answer . Well blow me down the guy took the key with the correct code put it into a small gadget [code reader I presume] pressed a button then placed the old key which would turn on the van but not start it pressed another button and hey presto it worked !! It took all of thirty seconds and he did not charge for the service I am impressed !! Howard .