Hi
later model cars have a new feature in the fuel tank that only allows you to insert a diesel nozzles some customer who have re fueled there cars incorrectly have had this device fitted also as a future precaution.if you look down the pipe on the car if you can see a flap this device is fitted and in this case when re fueling the car the nozzle has to fit in the pipe 100 % square this release the flap and allows the nozzle to be inserted.Some filling stations will have worn nozzles this is a common problem that we are seeing and feedback from our customers.
If there is no flap inserted then there is a restriction in the filling pipe and this will need to be removed to be inspected.
BMW Technician
city & guilds - Bmw Senior Technician