CL600 ABC sensors??
A few possible problems. You could be loosing pressure in the system (bad ABC pump, would most likely cause all corners to drop). You could be loosing pressure in the strut (strut leak, would cause just that strut to drop, or bad valve block, would cause whole left or right side to drop depending on which block). Bad ride height sensor would I would think only cause one corner to drop (there should be a sensor at each corner). It's also possible the programming is wrong, which could be indicative if someone tried to lower the car incorrectly through STAR. It does use an acceleration feed to raise and lower the whole car depending on speed, but that should only be a small adjustment in ride height.
It's hard to tell, but this might give you a better idea of how to examine the symptoms. You can also pull the codes with a reader (Autozone and similar stores can do this free, but it may not return the Mercedes specific codes you need). An independent Mercedes shop can pull the codes for you to see if that gives a hint.
Is the car lowered?



