Front left strut with abc on 2001 Mercedes-Benz S55 AMG

my left front strut is working but it is lower then the rest about 2in wen the car is off the left front drops to the ground do i need a new srut or a flash or could it be a sencor

Both or other things like a bad line etc. Best thing to do is too scan the Hydraulic Suspension system and then trace down the actual cause. I just worked on an AMG S55 with suspension issues and its suspension system really complex.
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Im real late here but if the car drops while its off it's the valve blocks that car has 2 on it and they are really expensive
go to your dealer and have codes pulled. You can get this done by asking for a diagnostic only. don't tell them whats wrong as they will follow that problem only. Ask for a suspension diagnostic with a printout. it costs about $150 depending on your location.