Page 386 of 539
385 Practical hints
What to do if …
Problem
Possible cause
Suggested solution
?
(USA only)
±
(Canada only)
The yellow engine malfunction
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 engine to
its limp-home (emergency op-
eration) mode (
page 192).
Have the vehicle checked as soon as
possible by an authorized
Mercedes-Benz Light Truck 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 identifi-
cation of system malfunctions through
the readout of diagnostic trouble
codes. It is located in the front left area
of the footwell next to the parking
brake pedal.
Page 387 of 539
386 Practical hintsWhat to do if …Problem
Possible cause
Suggested solution
?
(USA only)
±
(Canada only)
The yellow engine malfunction
indicator lamp comes on while
driving.
A 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 323).
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 Light Truck
Center.
Your fuel tank is empty.
After refueling start, turn off and
restart the engine three or four times in
succession.
The limp-home mode is canceled. You do
not need to have your vehicle checked.
Page 389 of 539
388 Practical hintsWhat to do if …Problem
Possible cause
Suggested solution
The yellow fuel tank reserve
warning lamp comes on while
driving.
The fuel level has gone below the reserve
mark.
Refuel at the next gas station
(page 323).
<
The red seat belt telltale comes
on and a warning chime sounds
for approximately six seconds af-
ter starting the engine with all
doors closed.
The seat belt telltale reminds you and your
passengers to fasten your seat belts before
driving off.
Fasten your seat belts.
The seat belt telltale goes out.
Page 393 of 539

392 Practical hintsWhat to do if …Warning!
G
Each tire, including the spare (if provided),
should be checked monthly when cold and
inflated to the inflation pressure recom-
mended by the vehicle manufacturer on the
vehicle placard or the tire inflation pressure
label. (If your vehicle has tires of a different
size than the size indicated on the vehicle
placard or the tire inflation pressure label,
you should consult the appropriate section
of this owner’s manual to determine the
proper tire inflation pressure). When the low
tire pressure telltale is illuminated, one or
more of your tires is significantly under-in-
flated. You should stop and check your tires
as soon as possible, and inflate them to the
proper pressure. Driving on a significantly
under-inflated tire causes the tire to over-
heat and can lead to tire failure. Under-infla-
tion also reduces fuel efficiency and tire
tread life, and may affect the vehicle’s han-
dling and stopping ability.
Your vehicle has also been equipped with a
TPMS malfunction telltale to indicate when
the system is not operating properly. When
the malfunction telltale is illuminated, the
system may not be able to detect or signal
low tire pressure as intended. TPMS mal-
functions may occur for a variety of reasons,
including the installation of incompatible
replacement tires on the vehicle. Always
check the TPMS malfunction telltale after
replacing one or more tires on your vehicle
to ensure that the replacement tires are
compatible with the TPMS.
Page 411 of 539

410 Practical hintsWhat to do if …Display symbol
Display messages
Possible cause
Possible solution
?
(USA only)
±
(Canada only)
Visit workshop
There may be a malfunction in
the:
Fuel injection system
Ignition system
Exhaust system
Fuel system
Have the measuring system checked by
an authorized Mercedes-Benz Light Truck
Center.
B
Coolant
Check level
The coolant level is too low.
Add coolant (
page 332).
If you have to add coolant frequently,
have the cooling system checked by an
authorized Mercedes-Benz Light Truck
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 can 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 Limited
Warranty.
Do not drive without sufficient amount
of coolant in the cooling system. The
engine will overheat causing major en-
gine damage.
Page 415 of 539

414 Practical hintsWhat to do if …Display symbol
Display messages
Possible cause
Possible solution
N
Check eng. oil level
when next refueling
The engine oil level is too low.
Check the engine oil level (
page 328)
(ML 500 only), or (
page 330) (ML 350
only).
USA only:Add 1 qt. engine oil
when next refuelingCanada only:Add 1 liter engine oil
when next refueling
The engine oil level is too low.
Add engine oil (
page 331) and check
the engine oil level (page 328) (ML 500
only), or (
page 330) (ML 350 only).
Engine oil level
Stop, engine off
There is no oil in the engine.
There is a danger of engine dam-
age.
Carefully bring the vehicle to a halt as
soon as possible.
Turn off the engine.
Add engine oil (
page 331) and check
the engine oil level (page 328) (ML 500
only), or (
page 330) (ML 350 only).
Engine oil level
Reduce oil level
You have added too much en-
gine oil. There is a risk of damag-
ing the engine or the catalytic
converter.
Have oil siphoned or drained off. Observe
all legal requirements with respect to its
disposal.
Page 416 of 539

415 Practical hints
What to do if …
When the
Add 1 qt. engine oil when
next refueling
(Canada:
1 liter
) mes-
sage appears while the engine is running
and at operating temperature, 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 ap-
proved oil specified in the Factory
Approved Service Products pamphlet.
Display symbol
Display messages
Possible cause
Possible solution
N
Engine oil level
Visit workshop
The engine oil has dropped to a
critical level.
Check the engine oil level (
page 328)
(ML 500 only), or (
page 330) (ML 350
only) and add oil as required
(
page 331).
If you must add engine oil frequently, have
the engine checked for possible leaks.
Oil sensor malfunction
Visit workshop
The measuring system is mal-
functioning.
Have the measuring system checked by
an authorized Mercedes-Benz Light Truck
Center.
!The engine oil level warnings should
not be ignored. Extended driving with
the symbol displayed could result in
serious engine damage that is not
covered by the Mercedes-Benz Limited
Warranty.
Page 417 of 539

416 Practical hintsWhat to do if …Display symbol
Display messages
Possible cause
Possible solution
A
Reserve fuel
The fuel level has dropped below
the reserve mark.
Refuel at the next gas station
(page 323).
Check gas cap
See Operator’s Manual
A loss of pressure has been de-
tected in the fuel system. The
fuel cap may not be closed prop-
erly or the fuel system may be
leaky.
Check the fuel cap (
page 323).
If it is not closed properly:
Close the fuel cap.
If it is closed properly:
Have the fuel system checked by an au-
thorized Mercedes-Benz Light Truck Cen-
ter.
a
Hood open
Trunk open
You are driving with the hood or
the tailgate open.
Close the hood (
page 326) or the tail-
gate (
page 120).
F
Key
Check battery
The SmartKey with
KEYLESS-GO* batteries are
discharged.
Change the batteries (
page 440).
Please do
not forget key
This display appears (for a maxi-
mum of 60 seconds) if the driv-
er’s door is opened with the
engine shut off and no SmartKey
in the starter switch.
This message is only a reminder.
Insert SmartKey in the starter switch.
Take the SmartKey with KEYLESS-GO*
with you when leaving the vehicle.