350 Practical hintsUnlocking/locking in an emergencyChanging batteries in the SmartKey/ SmartKey with KEYLESS-GO*
If the batteries in the SmartKey or the 
SmartKey with KEYLESS-GO* are dis-
charged, the vehicle can no longer be 
locked or unlocked. It is recommended to 
have the batteries replaced at an autho-
rized 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.SmartKey
1Mechanical key
2Battery compartment
Replacement batteries: Lithium, type 
CR 2025 or equivalent.
Remove mechanical key1 
(page 348).
Insert the mechanical key in side open-
ing and push gray slide.
The battery compartment is unlatched.
Pull the battery compartment out of the 
SmartKey housing in direction of ar-
row.
Remove the batteries.
Warning!
G
Keep the batteries out of reach of children.
If a battery is swallowed, seek medical help 
immediately.
iWhen changing batteries, always re-
place both batteries.
The required replacement batteries are 
available at any Mercedes-Benz 
Center. 
351 Practical hints
Unlocking/locking in an emergency
3Battery
4Contact spring
Using a lint-free cloth, insert new bat-
teries under the contact spring with the 
plus (+) side facing up. 
Return battery compartment into hous-
ing until it locks into place.SmartKey with KEYLESS-GO*
1Battery
2Tilt battery up
3Mechanical key
Replacement batteries: Lithium, type 
CR 2025 or equivalent.
Remove mechanical key (
page 348).
Insert the mechanical key in side open-
ing and push grey slide.
The battery compartment is unlatched.
Pull the battery compartment out of the 
SmartKey housing in direction of ar-
row.
Using mechanical key3, apply pres-
sure to position2.
Battery1 tilts up slightly.
Pull batteries1 out in direction of ar-
row.
Using a lint-free cloth, insert new bat-
teries with the plus (+) side facing up. 
Return battery compartment into hous-
ing until it locks into place.
iWhen changing batteries, always re-
place both batteries.
The required replacement batteries are 
available at any Mercedes-Benz 
Center.