Folding the rear seat backrest back
WARNING Risk of injury if the rear bench seat/rear seat and seat backrest are not engaged
If the rear bench seat/rear seat and seat backrest are not engaged they could fold forwards, e.g. when braking suddenly or in the event of an accident.
If this is the case, the vehicle occupant would be forced into the seat belt by the rear bench seat/rear seat or by the seat backrest. The seat belt cannot protect as intended and could result in additional injury.
Objects or loads in the boot cannot be restrained by the seat backrest.
Make sure that the seat backrest and the rear bench seat/rear seat are engaged before every trip.
NOTE Damage to the seat belt
The seat belt could become trapped and thus damaged when folding back the seat backrest.
Make sure that the seat belt is not trapped when folding back the seat backrest.
Move the driver's or front passenger seat forwards, if necessary.
Fold corresponding seat backrest 
back until it engages.
back until it engages. If the seat backrest is not engaged and locked, this will be shown in the multifunction display in the instrument cluster.