Page 362 of 480

361 Practical hints
What to do if …
Left display
Right display
Possible cause/consequence
Possible solution
T
Reduced
braking power!
Depress brake
pedal fully!
The electro-hydraulic brake system
is in emergency operation mode.
Considerably greater brake pedal
force is required and the stopping
distance is increased.
The maximum speed is limited to
55 mph (90 km/h).
Do not drive any further.
Stop the vehicle in a safe location or as soon
as it is safe to do so and notify an authorized
Mercedes-Benz Center.
Prevent the vehicle from rolling away by
blocking the wheels with wheel chocks or oth-
er sizable objects.
Call for Roadside Assistance.
USA only:;Canada only:3
Reduced
brake effect
Start engine
The battery has insufficient voltage
and cannot supply sufficient power
to the electro-hydraulic brake sys-
tem.
Start the engine.
The message disappears when sufficient
voltage is available.
Warning!
G
Inhalation of exhaust gas is hazardous to
your health. All exhaust gas contains carbon
monoxide, and inhaling it can cause uncon-
sciousness and lead to death.
Do not run the engine in confined areas
(such as a garage) which are not properly
ventilated.
Page 373 of 480

372 Practical hintsWhat to do if …Left display
Right display
Possible cause/consequence
Possible solution
O
Close hood
You are driving with the hood open.
Close the hood (
page 273).
I
Remove
key
You have forgotten to remove the
SmartKey from the starter switch.
Remove the SmartKey from the starter
switch.
Replace
key
The batteries in the SmartKey are
discharged.
Change the batteries (
page 389).
F
Key
Check battery
The batteries in the SmartKey with
KEYLESS-GO* are discharged.
Change the batteries (
page 389).
Don’t forget
key
This message appears (for a maxi-
mum of 60 seconds) if the driver’s
door is opened with the engine shut
off and no SmartKey in the starter
switch.
Message is only a reminder.
Insert SmartKey in the starter switch.
Take the SmartKey with KEYLESS-GO* with
you when leaving the vehicle.
KEYLESS GO
Check system
The KEYLESS-GO* system is mal-
functioning.
Visit an authorized Mercedes-Benz Center as
soon as possible.
KEYLESS-GO
Drive to
workshop
The KEYLESS-GO* system is mal-
functioning.
Visit an authorized Mercedes-Benz Center as
soon as possible.
Page 374 of 480

373 Practical hints
What to do if …
Left display
Right display
Possible cause/consequence
Possible solution
F
Key
not detected
The SmartKey with KEYLESS-GO* is
not recognized while the engine is
running because:
The SmartKey with
KEYLESS-GO* is not in the vehi-
cle.
There is strong radio-frequency
interference.
Stop the vehicle as soon as it is safe to do so.
Search for the SmartKey with KEYLESS-GO*
or continue to operate the vehicle with the
SmartKey.
Otherwise the vehicle cannot be centrally
locked nor can the engine be started again af-
ter the engine is stopped.
Key
not detected
The SmartKey with KEYLESS-GO* is
not recognized when attempting to
start the engine with the
KEYLESS-GO start/stop button* on
the gear selector lever because:
The SmartKey with
KEYLESS-GO* is not in the vehi-
cle.
The battery in the SmartKey
with KEYLESS-GO* is not insert-
ed properly or completely dis-
charged.
Change the position of the SmartKey with
KEYLESS-GO* in the vehicle.
Make sure the battery in the SmartKey with
KEYLESS-GO* is properly inserted
(page 390) and is not discharged
(page 106).
Operate the vehicle with the SmartKey if
necessary.
Page 385 of 480
384 Practical hintsWhere will I find ...?Vehicles with spare wheel
1Spare wheel
2Electric air pump
3Vehicle tool kit
4Battery for electrical consumers5Jack (under spare wheel)
6Wheel wrench (under spare wheel)Vehicles with TIREFIT kit
(SL 65 AMG only)
1TIREFIT kit
2Electric air pump
3Vehicle tool kit
4Battery for electrical consumers
5Wheel wrench
6Jack
Page 390 of 480

389 Practical hints
Replacing SmartKey batteries
Replacing SmartKey batteries
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
Replacement batteries: Lithium, type
CR 2025 or equivalent.
Remove mechanical key1
(page 385).
1Mechanical key
2Slide
3Battery compartment
Insert mechanical key1in direction
of arrow into side opening.
Using mechanical key1, push gray
slide2to unlatch battery compart-
ment 3.
Pull battery compartment3out of the
housing in direction of arrow.
Remove the batteries in direction of ar-
row.
4Battery
5Contact spring
Using a lint-free cloth, insert new bat-
teries 4 under contact spring 5 with
the positive terminal (+) facing up.
Return battery compartment 3 into
housing until it locks into place.
Slide mechanical key 1 back into the
SmartKey.
Check the operation of the SmartKey.
Warning!
G
Keep the batteries out of reach of children.
If a battery is swallowed, seek medical help
immediately.iWhen inserting batteries, make sure
they are clean and free of lint.
Page 391 of 480
390 Practical hintsReplacing SmartKey batteriesSmartKey with KEYLESS-GO*
Replacement battery: Lithium, type
CR 2025 or equivalent.
Remove the mechanical key
(page 385).
Take the battery compartment out of
the SmartKey housing (
page 389).1Battery
2Tilt battery up
3Mechanical key
Using mechanical key3, apply pres-
sure to position 2.
Battery 1 tilts up slightly.
Pull out battery 1 in direction of ar-
row.
Using a lint-free cloth, insert the new
battery under the contact spring with
the plus (+) side facing up.
Return the battery compartment into
the housing until it locks into place.
Slide mechanical key 1 back into the
SmartKey, see “SmartKey”
(page 389).
Check the operation of the SmartKey
with KEYLESS-GO.
iWhen replacing batteries, always re-
place both batteries. The required re-
placement batteries are available at
any authorized Mercedes-Benz Center.
Page 414 of 480
413 Practical hints
Batteries
Batteries
For more information on batteries, see
“Battery” (
page 279).
Your vehicle is equipped with two
batteries:
The starter battery
The battery for electrical consumers
(consumer battery), located in the
trunkThe starter battery is located on the
right-hand side of the engine compart-
ment.
1Positive terminal
2Negative terminalThe consumer battery is located on the
right-hand side of the trunk.
3Positive terminal
4Negative terminal
!The starter battery, its filler caps, and
the vent tube must always be securely
installed when the vehicle is in opera-
tion.
!The consumer battery located in the
trunk is a valve-regulated lead acid
(VRLA) battery, also referred to as
“fleece” battery. Such batteries do not
require topping-up of the electrolyte
level. VRLA batteries therefore do not
Page 415 of 480

414 Practical hintsBatteries
have cell caps and the battery cover is
non-removable. Do not attempt to
open the consumer battery as other-
wise the battery will be damaged.
Even though VRLA batteries do not
require topping-up of the electrolyte
level and cannot be opened to check
the electrolyte level, the battery condi-
tion must be checked periodically by
performing a battery conductance test.
Refer to Maintenance Booklet for bat-
tery condition testing intervals.
As with any other battery, disconnect
the consumer battery if you do not in-
tend to operate your vehicle for an
extended period of time to prevent bat-
tery discharge or connect an accessory
battery charge unit expressly approved
by Mercedes-Benz for your vehicle
model to maintain the battery charge.
Contact an authorized Mercedes-Benz
Center for further information.
Warning!
G
Failure to follow these instructions can re-
sult 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 termi-
nal clamps while the engine is running
or the SmartKey is in the starter switch.
Otherwise the alternator and other
electronic components could be se-
verely damaged.
Have the starter battery checked regu-
larly by an authorized Mercedes-Benz
Center.
Refer to Maintenance Booklet for main-
tenance intervals or contact an autho-
rized 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.