Purity

Assuring the purity of DEF is particularly important with respect to avoiding malfunctions in the exhaust gas aftertreatment system.

If DEF is pumped out of the DEF tank, e.g. during repair work, it must not be returned to the tank. The purity of the fluid can no longer be guaranteed.

service products, cleaning agents or dust) Impurities in DEF (e.g. due to other service products, cleaning agents or dust) lead to:
• increased emission values
• damage to the catalytic converter
• engine damage
• malfunctions in the BlueTEC exhaust gas aftertreatment system

    See also:

    System self-test
    After you have switched on the ignition, the system carries out a self-diagnosis. WARNING A malfunction in the system has been detected if one of the following conditions occurs: • the indi ...

    Restoring the factory settings
    ► Press the buttons simultaneously for approximately six seconds until the battery check lamp flashes twice. ...

    Activating/deactivating airrecirculation mode
    You can deactivate the flow of fresh air if unpleasant odors are entering the vehicle from outside. The air already inside the vehicle will then be recirculated. The operation of air-recirculat ...