Diagnostic MERCEDES-BENZ C300 2008 W204 Owner's Manual

325 Operation
Engine compartment
Engine compartment
Hood
Opening
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 vehicle and do not open the hood
until the engine has cooled down. 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 ap-
proximately 30 seconds or even restart af-
ter 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 (ig-
nition 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
cranked manually

378 Practical hints
What to do if …?
ProblemPossible cause/consequenceSuggested solution
±The yellow engine malfunc-
tion indicator lamp comes
on while driving.There is a malfunction in:

The fuel management system

The ignition system

The emission control system

Systems which affect emissions
Such malfunctions may result in excessive
emissions values and may switch the en-
gine to its limp-home (emergency opera-
tion) mode.
Have the vehicle checked as soon as
possible at an authorized
Mercedes-Benz Center.
An on-board diagnostic connector is
used by the service station to link the
vehicle to the shop diagnostics system.
It allows the accurate identification of
system malfunctions through the read-
out of diagnostic trouble codes. It is lo-
cated in the front left area of the
footwell next to the parking brake pedal.
iIn some states you may be required by law
to have the vehicle serviced as soon as the
engine malfunction indicator lamp comes on.
Check local requirements.

389 Practical hints
What to do if …?
Text messages
Display Possible cause/consequencePossible solution
ABS and ESP
Currently Unavailable
See Operator’s ManualABS and ESP® are not available due to a malfunction.
BAS and the hill start assist are also switched off. It
is possible that the self-diagnostics have not yet
been completed.
The brake system still functions normally.Drive a short distance with gentle turns above a
speed of 12 mph (20 km/h).
The message disappears when ABS and ESP
®
are again available.
The ABS and ESP® were deactivated because of in-
sufficient power supply. The charging voltage has
fallen below 10 volts. BAS and the hill start assist are
also deactivated.
The brake system still functions normally but without
the ABS and ESP
® available.
When the voltage is above this value again, the ABS
and ESP® are operational again and the message in
the multifunction display should disappear.
If the message in the multifunction display does not
disappear:
Have the generator (alternator) and the battery
checked.
ABS and ESP
Inoperative
See Operator’s ManualABS and ESP® are switched off due to a malfunction.
BAS and the hill start assist are also switched off.
The brake system still functions normally but without
the ABS and ESP
® available.
Continue driving with added caution. Wheels
may lock during hard braking, reducing steering
capability.
Have the system checked at an authorized
Mercedes-Benz Center as soon as possible.
Failure to follow these instructions increases the
risk of an accident.

397 Practical hints
What to do if …?
Symbol messages
Display Possible cause/consequencePossible solution
-ABS and ESP
Currently Unavailable
See Operator’s ManualABS and ESP® are not available due to a
malfunction. BAS and the hill start assist
are also switched off. It is possible that the
self-diagnostics have not yet been complet-
ed.
The brake system still functions normally.Drive a short distance with gentle turns
above a speed of 12 mph (20 km/h).
The message disappears when ABS and
ESP
® are again available.
The ABS and ESP® were deactivated be-
cause of insufficient power supply. The
charging voltage has fallen below 10 volts.
BAS and the hill start assist are also deacti-
vated.
The brake system still functions normally
but without the ABS and ESP
® available.
When the voltage is above this value again,
the ABS and ESP® are operational again and
the message in the multifunction display
should disappear.
If the message in the multifunction display
does not disappear:
Have the generator (alternator) and the
battery checked.

497 Index
L
Labels 462
Certification 462
Emission control information 463
Tire and Loading Information 335
Lamps, exterior 431
Light sensor 409
Lamps, indicator and warning
ABS 27, 59, 374
Air bag Off 40
Battery check lamp (SmartKey with
KEYLESS-GO* 77
Battery check lamp (SmartKey) 72
Brake warning lamp 27
Brakes 376
Engine diagnostics 27, 378
Engine malfunction 27, 378
ESP
®27, 376, 379, 380
Front passenger front air bag off 29,
45, 385, 386
Fuel reserve 380
High beam headlamps 27
Instrument cluster 374–383
Maintenance service indicator 362
Seat belt telltale 27, 380
SRS 27, 382Turn signals 27
Language 193
Language, Setting 168
LATCH-type child seat anchors see
Children in the vehicle
Lever
For cruise control 242
License plate lamps
Messages in display 411
Replacing bulbs 431, 437
Light alloy wheels, Cleaning 370
Light sensor
Message in display 409
Lighter see Cigarette lighter
Lighting 108
Automatic headlamp mode 109
Corner-illuminating front fog
lamps* 112
Daytime running lamp mode 110
Door entry lamps 116
High beam flasher 112
Instrument cluster illumination 148
Interior 114
Manual headlamp mode 108
Trunk 116
Limp-home mode 146Loading see Vehicle loading
Locator lighting 172
Lock button
Door handle (KEYLESS-GO*, Canada
only) 76, 125
Key, SmartKey 70
Key, SmartKey with KEYLESS-GO*
(Canada only) 73
Locking 133
Vehicle in an emergency 425
Locking knob 79
Loss of
Key, Mechanical 79
Key, SmartKey 79
Key, SmartKey with KEYLESS-GO*
(Canada only) 79
Service and Warranty Information
Booklet 461
Low beam headlamps
Replacing bulbs (Bi-Xenon*) 431
Replacing bulbs (Halogen) 431, 433
Lowering
Vehicle 445
Lubricants 476
Lumbar support* 91