It's possible that the indicator is incorrect, or that the level switch is incorrect. What makes you think that it's lost coolant? The level indicator should not poke out of the tank.It should be just level. Can you poke it down and will it bob up again?
'99 528i ('98/12 build). 282,000km BY29428/Royalrot
Breaking My Wallet since 2009
Mods: Stoptech SS brake hose, 280piece toolkit resting on trunk floor, Beisan VANOS seals, increasing amounts of duct tape and glue
'99 540i (grandfather's)