How do you fix a BMW 740il 2001 e38 obd p1347 fault?

You most likely have a faulty ignition coil on Cylinder 3 (Passenger side, third from the front of the car). Replace the Ignition Coil and you should be good to go. Next step would be to look into the Fuel injector for that cylinder. If the new coil doesn't do the trick, start with fuel injector cleaner and see if it improves