Mercedes-Benz 2015 M-Class Operator's Manual page 183

Important safety notes on the refilling
procedure
DEF is a water-soluble fluid for the exhaust
gas aftertreatment of diesel engines. It is:
not poisonous
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colorless and odorless
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not flammable
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When you open the DEF container, small
amounts of ammonia vapor may be released.
Ammonia vapors have a pungent odor and are
particularly irritating to the skin, to mucous
membranes and to the eyes. You may expe-
rience a burning sensation in your eyes, nose
and throat. Coughing and watering of the
eyes are possible.
Do not inhale ammonia vapors. Fill the DEF
tank only in well-ventilated areas.
DEF must not come into contact with your
skin, eyes or clothing and must not be swal-
lowed. Keep DEF away from children.
If you or other persons come into contact with
DEF, observe the following:
Rinse DEF from your skin immediately with
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soap and water.
If DEF comes into contact with your eyes,
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immediately rinse them thoroughly with
clean water. Seek medical assistance with-
out delay.
If DEF has been swallowed, rinse your
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mouth out immediately. Drink plenty of
water. Seek medical assistance without
delay.
Change out of clothing contaminated with
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DEF immediately.
! Only use DEF in accordance with
ISO 22241. Do not mix any additives with
DEF, and do not dilute DEF with water. This
may destroy the BlueTEC exhaust gas after-
treatment system.
! The vehicle must be parked on level
ground to fill the DEF tank. The DEF tank
can only be filled as intended with the vehi-
cle parked on a level surface. This avoids
false level readings. Filling the tank is not
permitted if the vehicle is not parked on a
level surface. There is a danger of overfill-
ing, which could result in damage to com-
ponents of the BlueTEC exhaust gas after-
treatment.
! Rinse surfaces that have come into con-
tact with DEF immediately with water or
remove DEF using a damp cloth and cold
water. If the DEF has already crystallized,
use a sponge and cold water to clean it. DEF
residues crystallize after time and contam-
inate the affected surfaces.
! DEF is not a fuel additive and must not be
added to the fuel tank. If DEF is added to
the fuel tank, this can lead to engine dam-
age.
For further information on DEF, see
( page 451).
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You will find further information on DEF in the
printed Operator's Manual under "Technical
data".
Opening the DEF filler cap
The fuel filler flap is unlocked or locked auto-
matically when you open or close the vehicle
with the SmartKey or with KEYLESS-GO.
Switch the ignition off.
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Press the fuel filler flap in the direction of
X
arrow :.
The fuel filler flap swings up.
Turn blue DEF filler cap ; counter-clock-
X
wise and remove it.
DEF filler cap ; is secured with a plastic
strip.
Refueling
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