MERCEDES-BENZ C350 4MATIC 2007 W203 Owner's Manual

340 Practical hints
What to do if …
Display messagePossible cause/
consequencePossible solution
Monitor the 56indicator lamp on the center console (page 27) and the mul-
tifunction display in the instrument cluster (
page 24) for the following:
With the seat unoccupied and the ignition turned on,

the 56indicator lamp on the center console should illuminate and remain
illuminated, indicating that the OCS (
page 64) has deactivated the air bag.

the message Front-pass. airbag enabled See Operator’s Manual or the mes-
sage
Front-pass. airbag disabled See Operator’s Manual should not appear
in the multifunction display at any time the seat is unoccupied. Wait at last 60 sec-
onds for the system to complete the necessary check cycles and to make sure
neither message appears in the multifunction display.
If above conditions are met, you can occupy the front passenger seat again. Depend-
ing on the front passenger classification sensed by the OCS (
page 64), the
56indicator lamp will remain illuminated or go out.
If above conditions are not met, the system is not working properly. Have the system
checked as soon as possible by an authorized Mercedes-Benz Center.
Warning!G
If the 56indicator lamp remains
illuminated with an adult occupant on the
front passenger seat even after performing
the above corrective steps, do not have anypassenger use the front passenger seat until
the system has been repaired.

341 Practical hints
What to do if …
Display messagePossible cause/consequencePossible solution
Run Flat Indicator
inoperative

The Run Flat Indicator* is malfunc-
tioning or has been switched off due
to an error.Have the Run Flat Indicator* checked by an
authorized Mercedes-Benz Center.
Check tires
Then restart
Run Flat Indicator

There was a warning message about
a loss in tire inflation pressure and
the Run Flat Indicator* has not been
reactivated yet.Make sure that the correct tire inflation pressure
is set for each tire.
Then reactivate the Run Flat Indicator*.
Tire pressure
Check tires

The Run Flat Indicator* indicates
that the pressure is too low in one or
more tires.Carefully bring the vehicle to a halt, avoiding
abrupt steering and braking maneuvers. Observe
the traffic situation around you.
Check and adjust the tire inflation pressure as
required (
page 290).
If necessary, change the wheel (page 377).
Reactivate the Run Flat Indicator* after adjusting
the tire inflation pressure values (
page 293).
Warning!G
Do not drive with a flat tire. A flat tire affects
the ability to steer or brake the vehicle.
You may lose control of the vehicle. Contin-
ued driving with a flat tire will cause exces-
sive heat build-up and possibly a fire.

342 Practical hints
What to do if …
Display messagePossible cause/consequencePossible solution
SRSRestraint
system
malfunction
Visit
workshopThe system is malfunctioning.Drive with added caution to the nearest
authorized Mercedes-Benz Center.
Warning!G
In the event a malfunction of the SRS is
indicated as outlined above, the SRS may
not be operational.
For your safety, we strongly recommend
that you visit an authorized Mercedes-Benz
Center immediately to have the system
checked; otherwise the SRS may not be
deployed when needed in an accident,
which could result in serious or fatal injury,
or it might deploy unexpectedly and
unnecessarily which could also result in
injury.

343 Practical hints
What to do if …
Symbol messages
Display symbolDisplay messagePossible cause/consequencePossible solution
#The battery is no longer charging.
Possible causes:

broken poly-V-belt

alternator malfunctioning
Stop immediately and check the
poly-V-belt in a safe location or as
soon as it is safe to do so.
If it is broken:
Do not continue to drive. Otherwise
the engine will overheat due to an
inoperative water pump which may
result in damage to the engine. Notify
an authorized Mercedes-Benz Center.
If it is intact:
Drive immediately to the nearest
authorized Mercedes-Benz Center.
Low voltage
Charge batteryThe battery has insufficient voltage.Start the engine (page 46).
Low voltage
Switch off ConsumersThe battery has insufficient voltage.Turn off unnecessary electrical
consumers.

344 Practical hints
What to do if …
Display symbolDisplay messagePossible cause/consequencePossible solution
;(USA only)
!(Canada only)
Release
parking brakeYou are driving with the parking brake
set.Release the parking brake
(
page 48).
2Brake
wearThe brake pads have reached their wear
limit.Have the brake pads replaced as soon
as possible.
;(USA only)
3(Canada only)
Check brake
fluid levelThere is insufficient brake fluid in the
reservoir.Risk of accident! Stop the vehicle and
notify an authorized Mercedes-Benz
Center. Do not add brake fluid! This
will not solve the problem.
Warning!G
Driving with the message Check brake
fluid level
displayed can result in an ac-
cident. Have your brake system checked im-
mediately. Do not add brake fluid before
checking the brake system. Overfilling the
brake fluid reservoir can result in spilling
brake fluid on hot engine parts and the
brake fluid catching fire. You could be seri-
ously burned.
!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.!Brake pad thickness must be visually in-
spected by a qualified technician at the intervals
specified in the Maintenance Booklet.

345 Practical hints
What to do if …
Display symbolDisplay messagePossible cause/consequencePossible solution
BTop up
coolant
See
Operator’s
ManualThe coolant level is too low.Add coolant (page 278).
If you have to add coolant frequently,
have the cooling system checked by
an authorized Mercedes-Benz Center.
Warning!G
Do not spill antifreeze on hot engine parts.
Antifreeze contains ethylene glycol which
may burn if it comes into contact with hot
engine parts. You could be seriously burned.
!Do not ignore the low engine coolant level
warning. Extended driving with the message and
symbol displayed may cause serious engine
damage not covered by the Mercedes-Benz Lim-
ited Warranty.
Do not drive without sufficient amount of coolant
in the cooling system. The engine will overheat
causing major engine damage.

346 Practical hints
What to do if …
Display symbolDisplay messagePossible cause/consequencePossible solution
•Coolant
Stop, turn
engine offThe coolant is too hot.
Among other possible causes, the
poly-V-belt could be broken.Stop the vehicle in a safe location or
as soon as it is safe to do so.
Apply the parking brake (page 54).
Turn off the engine.
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. Contact
an authorized Mercedes-Benz Center.
If it is intact:
Wait for the message to disappear be-
fore restarting the engine.
Doing otherwise could result in seri-
ous engine damage that is not covered
by the Mercedes-Benz Limited War-
ranty.
(Continued on next page)

347 Practical hints
What to do if …
During severe operating conditions and
stop-and-go city traffic, the coolant tem-
perature may rise close to 248°F (120°C).
Display symbolDisplay messagePossible cause/consequencePossible solution
Observe the coolant temperature gauge in
the instrument cluster (
page 24).
If the temperature rises again:
Contact an authorized Mercedes-Benz
Center immediately.
•The cooling fan for the coolant is mal-
functioning.Observe the coolant temperature gauge in the in-
strument cluster (
page 24).
Have the fan replaced as soon as possible.
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 coming from it.
Turn off the engine, get out of the vehicle
and do not stand near the vehicle until the
engine has cooled down.!The engine should not be operated with the
coolant temperature above 248°F (120°C). Do-
ing so may cause serious engine damage which
is not covered by the Mercedes-Benz Limited
Warranty.

348 Practical hints
What to do if …
When the message Check oil level at
next gas station
appears while the en-
gine is running and at operating tempera-
ture, the engine oil level has dropped to
approximately the minimum level.
When this occurs, the warning will first
come on intermittently and then stay on if
the oil level drops further.Visually check for oil leaks. If no obvious oil
leaks are noted, drive to the nearest
service station where the engine oil should
be topped to the required level with an
approved oil specified in the Factory
Approved Service Products pamphlet.
Display symbolDisplay messagePossible cause/consequencePossible solution
±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.
:Check oil level
at next gas stationThe engine oil has dropped to a critical
level.Check the engine oil level
(
page 276) and add oil as required
(
page 277).
If you must add engine oil frequently,
have the engine checked for possible
leaks.
!The engine oil level warnings should not be
ignored. Extended driving with the symbol dis-
played could result in serious engine damage
that is not covered by the Mercedes-Benz Limit-
ed Warranty.

349 Practical hints
What to do if …
Display symbolDisplay messagePossible cause/consequencePossible solution
4Gas cap
is openA loss of pressure has been detected in
the fuel system. The fuel cap may not be
closed properly or the fuel system may be
leaky.Check the fuel cap (page 271).
If it is not closed properly:
Close the fuel cap.
If it is closed properly:
Have the fuel system checked by an
authorized Mercedes-Benz Center.
IRemove keyYou have forgotten to remove the
SmartKey.Remove the SmartKey from the starter
switch.
Get a new
keyNo additional code available for
SmartKey.Change the SmartKey.
.3rd brake
lampThe high mounted brake lamp is
malfunctioning.Contact an authorized Mercedes-Benz
Center as soon as possible.
AUTO-Light
inoperativeThe light sensor is malfunctioning.
The headlamps switch on automatically.In the control system, set lamp opera-
tion to manual mode (
page 139).
Switch on the headlamps using the
exterior lamp switch.
Contact an authorized Mercedes-Benz
Center as soon as possible.