Page 232 of 370

238 OperationEngine compartmentCoolant level
The engine coolant is a mixture of water 
and anticorrosion/antifreeze. To check 
the coolant level, the vehicle must be 
parked on level ground and the engine 
must be cool. 
The coolant expansion tank is located on 
the passenger side of the engine compart-
ment.
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 334).
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 display in-
dicates 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 ½ 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.
S203 MY03_A.book  Page 238  Tuesday, January 28, 2003  2:22 PM 
         
        
        
     
        
        Page 240 of 370

246 OperationMaintenance
MaintenanceWe strongly recommend that you have 
your vehicle serviced by your authorized 
Mercedes-Benz Center, in accordance with 
the Service Booklet at the times called for 
by the FSS (Flexible Service System).
Failure to have the vehicle maintained in 
accordance with the Service Booklet at the 
designated times /mileage called for by 
the FSS may result in vehicle damage not 
covered by the Mercedes-Benz Limited 
Warranty.
FSS will notify you when your next service 
is due.
Approximately one month before your next 
service is due, one of the following mes-
sages will appear in the multifunction dis-
play while you are driving or when you 
switch on the ignition (example service A):SERVICE A IN XX DAYS 
SERVICE A IN XX MILES (KM)
SERVICE A DUE NOW!
The type of service due is indicated in the 
speedometer display field:9
Minor service (A)
½
Major service (B)
Clearing the service indicator
The service indicator is automatically 
cleared
after 10 seconds when you switch on 
the ignition or when reaching the ser-
vice threshold while driving
after 30 seconds, once the suggested 
service term has passed
You can also clear it yourself.
Press the reset knob on the instrument 
cluster (
page 22).
Service term exceeded
If you have exceeded the suggested ser-
vice term, you will see the following mes-
sage in the multifunction display:SERVICE A EXCEEDED BY XX DAYS 
SERVICE A EXCEEDED BY XX MILES (KM)The Mercedes-Benz Center will reset the 
service indicator following a completed 
service.
iThe interval between services depends 
on your driving habits. A gentle driving 
style, moderate engine speeds and the 
avoidance of short distance trips will 
lengthen the interval between services.
S203 MY03_A.book  Page 246  Tuesday, January 28, 2003  2:22 PM 
         
        
        
     
        
        Page 241 of 370

247 Operation
Maintenance
Calling up the service indicator
Switch ignition on.
The standard display of the control sys-
tem appears (
page 112).
Press button
k
 or
j
 on the mul-
tifunction steering wheel until the FSS 
indicator appears in the multifunction 
display.
Resetting the service indicator 
In the event that the service on your vehi-
cle is not carried out by an authorized 
Mercedes-Benz Center, you can reset the 
service indicator yourself.
Switch ignition on.
The standard display of the control sys-
tem appears (
page 112).
Press button
k
 or
j
 on the mul-
tifunction steering wheel until the FSS 
indicator appears in the multifunction 
display.
Press the reset knob for about four 
seconds.
This message appears in the tachome-
ter:DO YOU WANT TO RESET SERVICE INTER-
VAL? CONFIRM BY PRESSING RESET (R) 
BUTTON
To confirm, hold down the reset knob 
until you hear a signal.The service indicator now displays the 
reset interval.
iIf the battery is disconnected, the days 
of disconnection will not be included in 
the count shown by the service indica-
tor. To arrive at the true service dead-
line, you will need to subtract these 
days from the days shown in the ser-
vice indicator.
Do not confuse the service indicator 
with the engine oil level indicator
:
.
iIf the service indicator was inadvertent-
ly reset, have a Mercedes-Benz Center 
correct it.
Only reset if the proper service has 
been performed. Resetting the system 
without performing the proper service 
as called for by the FSS will cause the 
FSS to incorrectly determine the next 
service interval which will result in en-
gine damage not covered by the 
Mercedes-Benz Limited Warranty.
S203 MY03_A.book  Page 247  Tuesday, January 28, 2003  2:22 PM 
         
        
        
     
        
        Page 249 of 370
255 Practical hints
What to do if …
Problem
Possible cause
Suggested solution
-
The yellow ABS malfunction indi-
cator lamp comes on while driv-
ing.
The ABS has detected a malfunction and has 
switched off. The BAS and the ESP are also 
switched off (see messages in display).
The brake system is still functioning normally 
but without the ABS available.
Continue driving with added caution. 
Wheels may lock during hard braking 
reducing steering capability. 
Have the system checked at an autho-
rized Mercedes-Benz Center as soon 
as possible.
Failure to follow these instructions in-
creases the risk of an accident.
The charging voltage has fallen below 
10 volts and the ABS has switched off.
When the voltage is above this value 
again, the ABS is operational again.
If necessary, have the generator and 
battery checked.
S203 MY03_A.book  Page 255  Tuesday, January 28, 2003  2:22 PM 
         
        
        
     
        
        Page 254 of 370

260 Practical hintsWhat to do if …Messages in the display
The control system shows warning and 
malfunction messages in the multifunction 
display.
Certain warning and malfunction messag-
es are accompanied by an audible signal. 
Address these messages accordingly and 
follow the additional instructions given in 
this Operator’s Manual.
Selecting the malfunction memory menu in 
the control system (
page 115) displays 
both cleared and uncleared messages.
High-priority messages appear in the mul-
tifunction display in red color.
Certain messages of high priority cannot 
be cleared from the multifunction display 
using the reset knob on the instrument 
cluster.
Other messages of high priority and mes-
sages of less immediate priority (regular 
display colors) can be cleared from the multifunction display using the reset knob 
(
page 22) and are then stored in the mal-
function message memory (
page 115).
On the pages that follow, you will find a 
compilation of all the messages that may 
appear in the display. High priority mes-
sages appear on a red background.
Warning!
G
All categories of messages contain impor-
tant information which should be taken note 
of and, where a malfunction is indicated, ad-
dressed as soon as possible at an autho-
rized Mercedes-Benz Center.
Failure to repair the condition noted may 
cause damage not covered by the 
Mercedes-Benz Limited Warranty, or result 
in property damage or personal injury.Warning!
G
No messages will be displayed if either the 
instrument cluster or the multifunction dis-
play is inoperative.
Contact your nearest authorized 
Mercedes-Benz Center.
iTurning the key in starter switch to 
position2 causes all lamps as well as 
the multifunction display to come on. 
Ensure that they are all in working or-
der before starting your journey.
S203 MY03_A.book  Page 260  Tuesday, January 28, 2003  2:22 PM 
         
        
        
     
        
        Page 255 of 370
261 Practical hints
What to do if …
Display
Possible cause
Suggested solution
-
ABS SYSTEM
VISIT WORKSHOP!
The ABS has detected a malfunction and 
has switched off. The ESP and the BAS 
are also deactivated. The brake system is 
still functioning normally but without the 
ABS available.
Continue driving with added cau-
tion. Wheels will lock in hard brak-
ing reducing steering capability.
Have the system checked at an au-
thorized Mercedes-Benz Center as 
soon as possible.
Failure to follow these instructions in-
creases the risk of accident.
DISPLAY DEFECTIVE
VISIT WORKSHOP!
The ABS or the ABS display is malfunc-
tioning.
Continue driving with added cau-
tion. Wheels will lock in hard brak-
ing reducing steering capability.
Have the system checked at an au-
thorized Mercedes-Benz Center as 
soon as possible.
Failure to follow these instructions in-
creases the risk of accident.
S203 MY03_A.book  Page 261  Tuesday, January 28, 2003  2:22 PM 
         
        
        
     
        
        Page 256 of 370

262 Practical hintsWhat to do if …Display
Possible cause
Suggested solution
BAS
BRAKE ASSIST
NOT AVAILABLE!
The charging voltage has fallen below 
10 volts and the BAS has switched off.
When the voltage is above this val-
ue again, the BAS is operational 
again.
If necessary, have the generator 
and battery checked.
BRAKE ASSIST
VISIT WORKSHOP!
The BAS has detected a malfunction and 
switched off. The brake system is still 
functioning normally but without the BAS 
available.
Continue driving with added cau-
tion.
Have the system checked at an au-
thorized Mercedes-Benz Center as 
soon as possible.
Failure to follow these instructions in-
creases the risk of accident.
DISPLAY DEFECTIVE
VISIT WORKSHOP!
The BAS or the BAS display is malfunc-
tioning.
Continue driving with added cau-
tion.
Have the system checked at an au-
thorized Mercedes-Benz Center as 
soon as possible.
Failure to follow these instructions in-
creases the risk of accident.
S203 MY03_A.book  Page 262  Tuesday, January 28, 2003  2:22 PM 
         
        
        
     
        
        Page 257 of 370

263 Practical hints
What to do if …
Display
Possible cause
Suggested solution
#
BATTERY/ALTERNATOR
VISIT WORKSHOP!
The battery was charged with a battery 
charger or jump started.
Have the battery checked at a service 
station. 
The battery is no longer charging.
Possible causes:
alternator malfunctioning
broken poly-V-belt
Stop immediately and check the 
poly-V-belt.
If it is broken:
Do not continue to drive. Otherwise 
the engine will overheat due to an in-
operative water pump which may re-
sult in damage to the engine. Notify an 
authorized Mercedes-Benz Center.
If it is intact:
Drive immediately to the nearest au-
thorized Mercedes-Benz Center.
3 
(Canada only)
;
(USA only)
BRAKE PAD WEAR
VISIT WORKSHOP!
The brake pads have reached their wear lim-
it.
Have the brake pads replaced as soon 
as possible. 
!Brake pad thickness must be visually 
checked by a qualified technician at the 
intervals specified in the Service book-
let.
S203 MY03_A.book  Page 263  Tuesday, January 28, 2003  2:22 PM