For this reason the following work was performed: at first we took precautions to seal the filler necks of the fuel tanks and of the AdBlue reservoir. Easily accessible lock nuts and pipe connections of the fuel lines on the underbody of the vehicle were sealed using special wire and plastic crimp seals. The crimping tool bears a DEKRA logo and a registration number that are embossed into the plastic during the sealing procedure. The tool itself is unique and is permanently kept under our lock and key. In places where access to screw connections was more difficult, e.g. in the engine compartment, holes were drilled into the underbody panelling and the panels were tied together and to the chassis itself using the same types of seals. The access doors to the engine compartment and to the auxiliary heaters also were sealed. It also would have been possible, for instance, to tow the vehicles with the engine shut off. That's why the tow hooks were sealed as well.
As is the nature of regular-service buses, they do not have locking load compartments. That's why the sandbags were placed on the floor of the passenger compartment. The test lab therefore installed tubular frames behind the first axle in the interior, which were then covered with nets. Subsequently we fitted this construction with sealing wire and attached our seals. At the same time the rear doors of the vehicles were immobilised and sealed as well.