Mercedes-Benz E-Class Operator's Manual page 88

SmartKey
86
Make sure that the surface of the battery is
X
free of lint, grease and other contaminants.
Insert the front tabs of battery
X
compartment cover : into the housing
first and then press to close it.
Insert mechanical key ; into the
X
SmartKey ( page 84).
Y
Check the function of all SmartKey buttons
X
on the vehicle.