Page 193 of 474

192 Controls in detail
Automatic climate control*
Deactivating
It is possible to deactivate the air condi-
tioning (cooling) function of the automatic 
climate control system. The air in the 
vehicle will then no longer be cooled or 
dehumidified.
Press buttonœ (page 184).
The indicator lamp on the button goes 
out.
Activating
Moist air can fog up the windows. You 
can dehumidify the air with the air 
conditioning.
Press buttonœ (page 184).
The indicator lamp on the button 
comes on.
Residual heat and ventilation
With the engine switched off, it is possible 
to continue to heat or ventilate the interior 
for up to 30 minutes. This feature makes 
use of the residual heat produced by the 
engine.Activating
Switch off the ignition (page 37).
Press buttonT (page 184).
The indicator lamp on the button 
comes on. The display in the automatic 
climate control panel remains switched 
off.
Deactivating
Press buttonT (page 184) again.
The indicator lamp on the button goes 
out.
iHow long the system will provide heating 
depends on
the coolant temperature
the temperature set by the operator
The blower will run at speed setting1 regardless 
of the air volume control setting.
iThe residual heat is automatically turned off:
when the ignition is switched on (page 37)
after about 30 minutes
if the battery voltage drops 
     
        
        Page 290 of 474

289 Operation
Driving instructions
Emission control
Certain engine systems serve to keep the 
toxic components of the exhaust gases 
within permissible limits required by law.
These systems, of course, will function 
properly only when maintained strictly 
according to factory specifications. 
Any adjustments on the engine should 
therefore only be carried out by qualified 
Mercedes-Benz Center authorized techni-
cians.
Engine adjustments should not be altered 
in any way. Moreover, the specified service 
jobs must be carried out regularly accord-
ing to Mercedes-Benz servicing require-
ments. For details refer to the 
Maintenance Booklet.Coolant temperature
Warning!G
Inhalation of exhaust gas is hazardous to 
your health. All exhaust gas contains carbon 
monoxide (CO), and inhaling it can cause un-
consciousness and possible death.
Do not run the engine in confined areas 
(such as a garage) which are not properly 
ventilated. If you think that exhaust gas 
fumes are entering the vehicle while driving, 
have the cause determined and corrected 
immediately. If you must drive under these 
conditions, drive only with at least one win-
dow fully open at all times.Warning!G
Driving when your engine is overheated 
can cause some fluids, which may have 
leaked into the engine compartment, to 
catch fire. You could be seriously 
burned.
Steam from an overheated engine can 
cause serious burns and can occur just 
by opening the hood. Stay away from 
the engine if you see or hear steam com-
ing from it. 
Turn off the engine, get out of the vehicle 
and do not stand near the vehicle until the 
engine has cooled down. 
     
        
        Page 291 of 474
290 Operation
Driving instructions
!Excessive coolant temperature triggers a 
warning message in the multifunction display 
(
page 374).
The engine should not be operated with a 
coolant temperature above 248°F (120°C). 
Doing so may cause serious engine damage 
which is not covered by the Mercedes-Benz 
Limited Warranty.
iDuring severe operating conditions, e.g. 
stop-and-go city traffic, the coolant temperature 
may rise close to 248°F (120°C). 
     
        
        Page 293 of 474

292 Operation
At the gas station
Close the fuel filler flap.
Check regularly and before a long trip
Engine compartment 
(example illustration, SLK 350)
1Windshield washer system and head-
lamp cleaning system* reservoir
2Brake fluid reservoir
3Coolant expansion tankWindshield washer system and head-
lamp cleaning system*
For information on refilling the reservoir, 
see “Windshield washer system and 
headlamp cleaning system*” 
(
page 301).
Brake fluid
For information on brake fluid, see “Fuels, 
coolants, lubricants, etc.” (
page 451).
iMake sure to close the fuel filler flap before 
locking your vehicle as the flap locking pin 
prevents closing after you have locked the 
vehicle.
iOnly use premium unleaded gasoline with a 
minimum Posted Octane Rating of 91 (average 
of 96 RON/86 MON).
Information on gasoline quality can normally be 
found on the fuel pump. Please contact gas 
station personnel in case labels on the pump 
cannot be found.
For more information on gasoline, see “Premium 
unleaded gasoline” (
page 454), refer to the 
Factory Approved Service Products pamphlet 
(USA only), or contact an authorized 
Mercedes-Benz-Center.
iLeaving the engine running and the fuel cap 
open can cause the yellow fuel tank reserve 
warning lamp to flash and the?malfunction 
indicator lamp (USA only) or the 
±malfunction indicator lamp (Canada only) 
to illuminate.
For more information, see “Practical hints” 
(
page 351).
iFor opening the hood, see “Hood” 
(
page 294).
!If you find that the brake fluid in the brake 
fluid reservoir has fallen to the minimum mark or 
below, have the brake system checked for brake 
pad thickness and leaks immediately. Notify an 
authorized Mercedes-Benz Center immediately. 
Do not add brake fluid as this will not solve the 
problem.
For more information, see “Practical hints” 
(
page 350).
 
     
        
        Page 294 of 474
293 Operation
At the gas station
Coolant
For normal replenishing, use water 
(potable water quality).
For more information on coolant, see 
“Coolant level” (
page 300) and “Fuels, 
coolants, lubricants, etc.” (
page 451).
Engine oil level
For information on engine oil, see “Engine 
oil” (
page 296).Vehicle lighting
Check function and cleanliness.
For more information on vehicle lighting, 
see “Replacing bulbs” (
page 400).
For information on switching on the exteri-
or lighting, see “Exterior lamp switch” 
(
page 109).
Tire inflation pressure
For information on tire inflation pressure, 
see “Important notes on tire inflation 
pressure” (
page 313). 
     
        
        Page 295 of 474

294 Operation
Engine compartment
Hood
Opening
1Hood lock release lever
Warning!G
Do not pull the release lever while the vehi-
cle is in motion. Otherwise the hood could 
be forced open by passing air flow.
This could cause the hood to come loose 
and injure you and/or others.
Warning!G
If you see flames or smoke coming from the 
engine compartment, or if the coolant tem-
perature gauge indicates that the engine is 
overheated, do not open the hood. Move 
away from the vehicle and do not open the 
hood until the engine has cooled. If neces-
sary, call the fire department.
Warning!G
You could be injured when the hood is open 
– even when the engine is turned off.
Parts of the engine can become very hot. To 
prevent burns, let the engine cool off com-
pletely before touching any components on 
the vehicle. Comply with all relevant safety 
precautions.
Warning!G
To help prevent personal injury, stay clear of 
moving parts when the hood is open and the 
engine is running.
The radiator fan may continue to run for 
approximately 30 seconds or may even 
restart after the engine has been turned off. 
Stay clear of fan blades.
Warning!G
The engine is equipped with a transistorized 
ignition system. Because of the high voltage 
it is dangerous to touch any components 
(ignition coils, spark plug sockets, 
diagnostic socket) of the ignition system
with the engine running
while starting the engine
if ignition is “on” and the engine is 
turned manually 
     
        
        Page 298 of 474

297 Operation
Engine compartment
One of the following messages will 
subsequently appear in the multifunc-
tion display:
Engine Oil Level
OK
Add 1.0 qt. (Canada: 1.0 liter)
to reach max. oil level.
Add 1.5 qts. (Canada: 
1.5 liters)
to reach max. oil level.
Add 2.0 qts. (Canada: 
2.0 liters)
to reach max. oil level.
If necessary, add engine oil.
For adding engine oil, see “Adding 
engine oil” (
page 299).
For more information on engine oil, see 
“Fuels, coolants, lubricants, etc.” 
(
page 451).Other display messages
If the ignition is not switched on, the fol-
lowing message will appear:
Turn on ignition
to see engine oil level
.
Switch on the ignition (page 37).
If you see the message:
Observe
Waiting Time
If engine is at operating temperature, 
wait 5 minutes before repeating check 
procedure.
If engine is not at operating tempera-
ture yet, you must wait 30 minutes 
before checking oil.If you see the message:
Cannot check engine oil level
with engine on.
Turn off the engine.
If the engine is at operating tempera-
ture, wait 5 minutes before checking 
oil.
If the engine is not at operating 
temperature yet, you must wait 
30 minutes before checking oil.
iIf you want to interrupt the checking 
procedure, press buttonk orj on the 
multifunction steering wheel (
page 122).
iIf you want to interrupt the checking 
procedure, press buttonk orj on the 
multifunction steering wheel (
page 122). 
     
        
        Page 300 of 474

299 Operation
Engine compartment
Pull out oil dipstick1 again after 
approximately 3 seconds to obtain 
accurate reading.
The oil level is correct when it is be-
tween the lower (min) mark3 and 
upper (max) mark2 of oil dipstick1.
If necessary, add engine oil.
For adding engine oil, see “Adding 
engine oil” (
page 299).
For more information on engine oil, see 
“Fuels, coolants, lubricants, etc.” 
(
page 451).
For more information on messages in the 
multifunction display concerning engine 
oil, see the “Practical hints” section 
(
page 360).Adding engine oil
SLK 350 (example illustration)
1Filler cap
SLK 55 AMG
1Filler cap
iThe filling quantity between the upper and 
lower marks on the oil dipstick is approximately 
2.1 US qt. (2.0 l).
!Only use approved engine oils and oil filters 
required for vehicles with Maintenance System. 
For a listing of approved engine oils and oil 
filters, refer to the Factory Approved Service 
Products pamphlet (USA only) in your vehicle 
literature portfolio, or contact an authorized 
Mercedes-Benz Center.
Using engine oils and oil filters of specification 
other than those expressly required for the 
Maintenance System, or changing of oil and oil 
filter at change intervals longer than those called 
for by the Maintenance System will result in 
engine or emission control system damage not 
covered by the Mercedes-Benz Limited 
Warranty.