WARNING
Make sure
• DEF does not come into contact with skin, eyes, or clothing
• to keep DEF out of the reach of children If you and/or others have come into contact with DEF:
• If DEF has gotten into contact with eyes, flush with plenty of water immediately and seek medical help.
• Clean affected skin immediately with plenty of water.
• If DEF was swallowed, rinse mouth immediately with plenty of water and drink plenty of water. Consult a physician.

WARNING
If you open the DEF tank cap at high temperatures, ammonia vapors can be released.
Ammonia vapors have a pungent odor and are particularly irritating to:
• skin
• mucous membranes
• eyes
You may experience a burning sensation in your eyes, nose and throat, as well as coughing and watering of the eyes.
Do not inhale any ammonia vapors that may be released. Only refill the DEF tank in well ventilated areas.

Only use DEF that complies with ISO 22241. Do not add any special additives to DEF and do not thin DEF with water. This could destroy the BlueTEC exhaust gas aftertreatment.

If the outside temperature is lower than Ò11 °C, damage may occur when topping up.
If DEF is frozen and there is an active warning indicator, topping up may not be possible.
Park the vehicle in a warmer place, e.g. in a garage, until DEF has become fluid again.
Filling is then possible again. Alternatively, have the DEF tank refilled at a qualified specialist workshop.

Rinse surfaces that have come into contact 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 contaminate 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 damage.

If you are adding between maintenance intervals, add approximately 1 gallon (3.8 l) of DEF to the DEF tank. One gallon (3.8 l) of DEF is approximately 2 DEF refill bottles.
Then, have the DEF supply checked and filled completely if necessary. For this purpose, Mercedes-Benz recommends a qualified specialist workshop.

Further information on DEF.

The filler neck for DEF is located under the "Minispare" emergency spare wheel in the trunk floor.

Switch off the ignition.

Open the trunk.

Lift up the trunk floor.

Turn the "Minispare" emergency spare wheel fastening in the direction of the arrow and remove it.

Remove the "Minispare" emergency spare wheel.

Turn DEF cap 1 counter-clockwise and remove it.

Turn DEF filler cap 2 counter-clockwise and open it.

Filler cap 2 is secured with a plastic strap.

Unscrew the covering cap from DEF refill bottle 3.

Place DEF refill bottle 3 on the filler neck as shown and screw on clockwise handtight.

Only screw on the DEF refill bottle handtight.

It could otherwise be damaged.

Press DEF refill bottle 3 down.

The DEF tank is filled. This may take up to one minute.

If the DEF refill bottle is no longer pressed down, the filling process stops and the partially emptied bottle can be removed.

Release DEF refill bottle 3.

Turn DEF refill bottle 3 counter-clockwise and remove it.

Place DEF filler cap 2 on the filler neck and turn it clockwise.

Insert DEF cap 1 as shown and turn it clockwise as far as it will go.

Place the "Minispare" emergency spare wheel in the emergency spare wheel well above the DEF tank.

Insert the "Minispare" emergency spare wheel fastening and tighten clockwise.

Fold the trunk floor down.

Close the trunk lid.

Drive at a speed above 10 mph (16 km/h).

The Check Additive See Operator's Manual message goes out after approximately one minute.

If the Check Additive See Operator's Manual message remains shown in the multifunction display, add an additional bottle of DEF.

Then, have the DEF supply checked at a qualified specialist workshop and completely refilled if necessary.