High outside temperatures

If DEF heats up to over 122 °F (50 °C ) for extended periods, e.g. as a result of direct sunlight on the DEF reservoir, DEF can decompose. Ammonia vapors develop as a result.

When opening the filler cap of the DEF tank WARNING
When opening the filler cap of the DEF tank ammonia gas vapors may escape. Refill DEF in a well ventilated area only. Ammonia gas vapors have a pungent odor and are particularly irritating for your skin, mucous membranes, and eyes. Inhaling ammonia gas vapors will cause burning eyes, nose, and throat, as well as coughing and watering eyes.

    See also:

    Important notes on use
    To function properly, BlueTEC exhaust gas aftertreatment must be operated with the reducing agent DEF. When the DEF supply has almost run out, the Check Additive See Operator's Manual message ...

    Floormat on the driver's side
    WARNING Whenever you are using a floormat, make sure there is enough clearance and that the floormat is securely fastened. The floormat should always be securely fastened using the fastening ...

    Important notes on use
    To function properly, BlueTEC exhaust gas aftertreatment must be operated with the reducing agent DEF. Adding DEF is one of the tasks performed during maintenance. Under normal operating condi ...