Posting just for information….
My Neff U1661N0GB lower oven started misbehaving after one of the two bulbs in the oven failed. The fan oven position did not work( and no light either), but the non fan worked (again no light) and on other postions of the switch some features worked, some didn’t, including the lights. So really mixed up set of faults.
Following a suggestion on another post, I removed left hand (main oven ) control board and found a track had vapourized, along with a pin on the relay it was wired to. Replaced relay @ £0.91, and repaired the track. Oven is now working fine. It appears that the bulb must have failed in a mode where it shorts, and created an excessive current on the pcb, and the fusing in the spur connection and main box didn’t protect it.