Page 234 of 376

234 OperationAt the gas station
Check regularly and before a long trip
1Coolant level
More information on the coolant level 
can be found in the “Operation” section 
(
page 238).
2Brake fluid (fuse box cover removed)
More information on brake fluid can be 
found in the “Technical data” section 
(page 332).
Removing fuse box cover 
(page 312).
3Windshield washer and headlamp 
cleaning system*
For more information on refilling the 
reservoir, see the “Operation” section 
(page 241).Engine oil level
More information on engine oil can be 
found in the “Operation” section 
(
page 236).
Opening hood (
page 235).
Coolant
For normal replenishing, use water (pota-
ble water quality). More information on 
coolant can be found in the “Operation” 
section (
page 238).
Vehicle lighting
Check function and cleanliness. For more 
information on replacing light bulbs, see 
the “Practical hints” section (
page 290).
Exterior lamp switch (
page 101).
Tire inflation pressure
More information on tire inflation pressure 
can be found in the “Operation” section 
(
page 243).
iUse only 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.
More information on gasoline can be 
found in the Factory Approved Service 
Products pamphlet.
Flexible Fuel Vehicles (MY 2003 
Mercedes-Benz C 320 models, except 
those equipped with manual transmis-
sion or 4MATIC*): 
More information on Flexible Fuel Vehi-
cles can be found in the “Technical da-
ta” section (
page 334).
iLeaving the engine running and the fuel 
cap open can cause the
? 
lamp to 
illuminate.
See also “Practical hints” section 
(
page 259). 
     
        
        Page 239 of 376

239 Operation
Engine compartment
1Coolant expansion tank
Using a rag, turn the cap slowly approx-
imately one half turn to the left to re-
lease any excess pressure.
Continue turning the cap to the left and 
remove it.The coolant level is correct if the level 
for cold coolant: reaches the black 
top part of the reservoir
for warm coolant: is approx. 0.6 in 
(1.5 cm) higher
Add coolant as required.
Replace and tighten cap.
More information on coolant can be found 
in the “Technical data” section 
(
page 336).
Warning!
G
In order to avoid any possibly serious burns:
Use extreme caution when opening the 
hood if there are any signs of steam or 
coolant leaking from the cooling system, 
or if the coolant temperature gauge indi-
cates that the coolant is overheated.
Do not remove pressure cap on coolant 
reservoir if engine temperature is 
above 194°F (90°C). Allow engine to 
cool down before removing cap. The 
coolant reservoir contains hot fluid and 
is under pressure.
Using a rag, slowly open the cap approx-
imately 
1/2 turn to relieve excess pres-
sure. If opened immediately, scalding 
hot fluid and steam will be blown out un-
der pressure.
Do not spill antifreeze on hot engine 
parts. Antifreeze contains ethylene gly-
col which may burn if it comes into con-
tact with hot engine parts. 
     
        
        Page 278 of 376
278 Practical hintsWhat to do if …Display
Possible cause
Suggested solution
#
UNDERVOLTAGE
ENGINE ON!
The battery has insufficient voltage and 
can no longer supply the convenience 
functions such as seat heater*.
Start the engine (
page 44).
UNDERVOLTAGE
SWITCH CONSUMERS OFF!
The battery is malfunctioning.
Have the battery checked at a service 
station.
G
VISIT WORKSHOP!
DISPLAY DEFECTIVE
The instrument cluster display is 
malfunctioning.
Continue driving with added caution.
Visit an authorized Mercedes-Benz 
Center as soon as possible.
±
VISIT WORKSHOP!
DISPLAY DEFECTIVE
Certain electronic systems are unable to 
relay information to the control system. 
The following systems may have failed:
Coolant temperature display
Tachometer
Cruise control display
Have the electronic systems checked 
by an authorized Mercedes-Benz 
Center (
page 259).
W
WASHER FLUID
CHECK LEVEL!
The fluid level has dropped to about 
1/3 
of total reservoir capacity.
Add washer fluid (
page 241). 
     
        
        Page 338 of 376

338 Technical dataFuels, coolants, lubricants etc.Windshield washer and headlamp cleaning* system
Both the windshield and headlamp washer 
systems are supplied from the windshield 
washer fluid reservoir.
The washer fluid reservoir has a capacity of 
approx.
6.4 US qt (6.0 l) in vehicles with head-
lamp cleaning system*
3.2 US qt (3.0 l) in vehicles without 
headlamp cleaning system
Refill the reservoir with MB Windshield 
Washer Concentrate “S” and water (or 
concentrate and commercially avail-
able premixed windshield washer sol-
vent/antifreeze, depending on ambient 
temperatures).Washer fluid mixing ratio
For temperatures above freezing use 
MB Windshield Washer Concentrate “S” 
and water:
1part“S” to 100parts water
[40ml“S” to 1gallon (4l) water]
For temperatures below freezing use 
MB Windshield Washer Concentrate “S” 
and commercially available premixed 
windshield washer solvent / antifreeze:
1part“S” to 100parts solvent
[40ml“S” to 1gallon (4l) solvent]
Warning!
G
Washer solvent/antifreeze is highly flamma-
ble. Do not spill washer solvent/antifreeze 
on hot engine parts, because it may burn. 
You can be seriously burned.