I cannot offer any helpful advice but, as a Plus 4 GDI owner, I'd be very interested to learn what the fault was when you find out. Mine refused to start once after being laid up for a few weeks. Everything was checked by the local dealer's engineer with his laptop software and nothing amiss. Then, finally, it spluttered into life. We never did find out what the problem was and, mercifully, it has not recurred.