Page 114 of 489

113 Controls in detail
Locking and unlocking
Checking the batteries in the SmartKey 
or SmartKey with KEYLESS-GO*
Press button ‹or Œ.
The battery check lamp (
page 104) 
or (
page 108) comes on briefly to in-
dicate that the SmartKey or SmartKey 
with KEYLESS-GO batteries are in 
order.Loss of the SmartKey or SmartKey with 
KEYLESS-GO*
If you lose your SmartKey or SmartKey 
with KEYLESS-GO or the mechanical key, 
you should do the following:
Have the SmartKey or SmartKey with 
KEYLESS-GO deactivated by an 
authorized Mercedes-Benz Center.
Report the loss of the SmartKey or 
SmartKey with KEYLESS-GO or the 
mechanical key to your car insurance 
company immediately.
Have the mechanical lock replaced if 
necessary.
Any authorized Mercedes-Benz Center will 
be glad to supply you with a replacement. 
Opening the doors from the inside
You can open a locked door from the in-
side. Open door only when conditions are 
safe to do so.
1Locking knob
2Inside door handle
Pull on inside door handle2 in direc-
tion of arrow.
If the door was locked, locking knob1 
will move up.
Opening a door causes its window to 
open slightly. It will fully close when the 
door is shut.
iIf the battery check lamp does not come 
on briefly during check, then the SmartKey or 
SmartKey with KEYLESS-GO batteries are 
discharged.
Replace the batteries (
page 407). 
You can obtain the required batteries at any 
authorized Mercedes-Benz Center.
iIf the batteries are checked within signal 
range of the vehicle, pressing the‹orŒ 
button will lock or unlock the vehicle 
accordingly.  
     
        
        Page 408 of 489

407 Practical hints
Replacing SmartKey batteries
Replacing SmartKey batteries
If the batteries in the SmartKey or the 
SmartKey with KEYLESS-GO* are 
discharged, the vehicle can no longer be 
locked or unlocked. It is recommended 
to have the batteries replaced at an 
authorized Mercedes-Benz Center.Batteries contain materials that can harm 
the environment if disposed of improperly. 
Recycling of batteries is the preferred 
method of disposal. Many states require 
sellers of batteries to accept old batteries 
for recycling.Remove the mechanical key from the 
SmartKey or SmartKey with 
KEYLESS-GO* (
page 403).
1Mechanical key
2Battery compartment
Insert mechanical key 1 into opening.
Press mechanical key 1 in direction of 
arrow.
The battery compartment is unlatched.
Pull battery compartment 2 out of the 
housing.
Warning!G
Batteries contain poisonous and corrosive 
substances. Therefore keep the batteries 
out of reach of children.
If a battery is swallowed, seek medical help 
immediately.
Warning!G
SmartKey batteries contain Perchlorate 
material, which may require special handling 
and regard for the environment. Check with 
your local government’s disposal guidelines. 
California residents, see 
http://www.dtsc.ca.gov/HazardousWaste
/Perchlorate/index.cfm.
iWhen inserting batteries, make sure they 
are clean and free of lint.
iWhen replacing batteries, always replace 
both batteries.
The required replacement batteries (Lithium, 
type CR 2025 or equivalent) are available at any 
authorized Mercedes-Benz Center.
 
     
        
        Page 429 of 489

428 Practical hints
Batteries
!The factory-equipped VRLA battery is 
leak-proofed. Only use a battery as replacement 
that has the same security features and is of 
identical size, voltage, and capacity as the 
factory-equipped battery.
The battery, the battery ventilation and the 
lateral plug must always be securely installed 
when the vehicle is in operation.
Warning!G
Failure to follow these instructions can 
result in severe injury or death.
Never lean over batteries while connecting, 
you might get injured.
Battery fluid contains sulfuric acid. Do not 
allow this fluid to come in contact with eyes, 
skin or clothing. In case it does, immediately 
flush affected area with water and seek 
medical help if necessary.
A battery will also produce hydrogen gas, 
which is flammable and explosive. Keep 
flames or sparks away from battery, avoid 
improper connection of jumper cables, 
smoking, etc.
!Never loosen or detach battery terminal 
clamps while the engine is running or the 
SmartKey is in the starter switch. Otherwise the 
alternator and other electronic components 
could be severely damaged.
Have the starter battery checked regularly by an 
authorized Mercedes-Benz Center.
Refer to Maintenance Booklet for maintenance 
intervals or contact an authorized 
Mercedes-Benz Center for further information.
Warning!G
Do not place metal objects on the battery as 
this could result in a short circuit. 
Use leak-proof batteries only to avoid the 
risk of acid burns in the event of an acci-
dent.
Warning!G
The brake system requires electrical power 
to operate.
A malfunction in the vehicle’s power supply 
or electrical system may impair brake sys-
tem operation and switch it into its emer-
gency operation mode. The same applies if 
battery is disconnected. To brake, the driver 
must then apply significantly greater brake 
pedal pressure and depress the pedal much 
further to obtain the expected braking ef-
fect. If necessary, apply full pressure to the 
brake pedal. Brakes are only applied to the 
front wheels. 
Stopping distance is increased! Adjust your 
driving style accordingly. For more informa-
tion, see “Electro-hydraulic brake system” 
(
page 94).