I have an AEG Competence B4140-1 built-in fan oven which I installed about 7 years ago without problems. Twice in the last few days when switching it off having been using it in fan oven mode, the rear fan element does not switch off. So I have an oven, switched off, with a cooling fan gently running and a bright red element inside the fan casing at the back. I had to isolate the oven at the wall to kill it. Restore the power again, but with the oven switched off, the element shines bright red again. Once the oven is cool and I restore the power all is OK. After the first incident I did a pyrolytic clean to get rid of gunge inside, but the latest incident is since then.
It is on the same isolator as the electric hob which is a pain - lesson learned.
Looks to me like a sticking relay somewhere. I cannot find a wiring diagram online though. Anyone had a similar problem and fixed it. I am about to delve inside the oven!
Regards Bruce