Of these 4, it was the evaporative system causing the code in my 550i.
. It can be a faulty cap that isn't sealing.
. It can be a leak in the evaporative emissions control system
. It can be a fault in the air pump that creates pressure in the fuel tank and evaporative emissions control system
. It can be a sensor in that system.

__________________
Richard
Sir Snaps-a-lot, 9 Time Dragon Slayer (54 runs!)
2011 X5 50i Alpine White, Biege Nappa /Lt Poplar M Sport
2009 Z4 35i, Black Sapphire/Ivory-Black/Anthracite

Gone but not forgotten: '08 550i, '06 X3, '06 650i, '02 M5, '99 540i