Miele DG 5070 Operating And Installation Instructions page 49

... a whistling sound is heard when the appliance is
switched on again.
When the door is closed, the pressure has to equalise, which
can cause a whistling sound. This is not a fault.
... F and a number appear in the display.
This combination indicates a fault.
– F 20: The appliance does not heat up.
Check whether the water container has been pushed right
into the appliance so that it connects.
Switch the appliance off and then back on again.
– A fault message will appear if the temperature of the oven
compartment has not risen by at least 2 °C within
5 minutes of the start of the heating up phase. This can
occur if, for example, a large quantity of frozen food is
being prepared.
– Lightly lubricate the coupling seal on the water container
with silicone grease, as described in "Cleaning and care /
Water container / Coupling seal".
If the appliance still will not start, switch it off and contact the
Miele Service Department.
– Other fault messages:
Call the Service department.
Problem solving guide
49