Siemens Double Oven Clock Fault

Went to a Siemens Double Oven (Enr HB13M550B/03, Model HBB-AP63-7) with a Clock Fault. The clock continuously flashes side to side of the display. When the “clock” button (on left) is pressed it displays “F5 Kg”

Is this a Fault Code ?? – can anyone help here. I am about to order a new clock (around a hundred quid) but am worried that the flashing and the “F5” indicate a fault and the clock is in fact OK.

All functions appear to work on the double oven, including the cooling fan in the top.

Any help appreciated. As we know well, the worst scenario is to fit an expensive new part only to find the original fault is still there!!

Thanks