Mercedes-Benz 2009 R-Class Operator's Manual page 314

Practical hints
Vehicle status messages in the multifunction display
Display messages
G Warning!
If the 59 indicator lamp remains out even after performing the above corrective steps, do not have any children 12 years old
and under and other small individuals use the front passenger seat until the system has been repaired.
312
Possible cause/consequence Possible solution
OCS, the 59 indicator lamp will
remain illuminated or go out.
If above conditions are not met, the system is not
working properly. Have the system checked as
soon as possible at an authorized Mercedes-Benz
Center.