Engine wont stop!?

[Richn83]

I wouldn't think that the immobiliser has anything to do with the ignition after its initial check 5 seconds after first start up it wont keep checking for the key.

[swedishfireball]

Could be fused contacts on the ignition relay ( if MK5s still use them) Do you know if the dash was still on when the key was taken out?

They do have relays as mine went very recently.. pain in the butt. Could certainly be a cause of this issue.

[RSam84]

Id go with a relay or a fuse, we had a renault 5 that wouldnt turn off once started turned out to be relay had died in fusebox and screwed it all up!

[VC]

Update

Spoken again to him and he's said the dash lights stay on.

His adventure tonight to get petrol and he bumped it to a stop at the pump and filled up. It then wouldn't start up and all the dash lights died, the satnav went black with a small red cross on it. He pressed the screen and fiddled with it for about ten minutes then all of a sudden the dash lit up so he tried the car and it started, everything working fine.

Drove it home and it wouldn't turn off so he put the key back in and tried again and then it did turn off

So weird

The car has also had a diagnostic check when the battery was changed and no fault codes returned. He bought it off me at the start of the summer and it's only done about 100 miles since and the only change was the battery dying and a new one going on

He's going to put himself at the mercy of VW themselves tomorrow to see what they think about it all