Have you got a cloudy white covering on the metal in your washer and on your pots?
I had the same lights after 3 weeks with a FDW65a (same internals I think) and added salt to the machine, ran it about 3 times and the problem has cleared. Previously engineers had told me not to use rinse aid and salt with 3 in 1 tablets. If you are in a hard water area, this is wrong (as Salt is a water softner).
These lights indicate the heating circuit has failed. If you have heat from your machine, this is not the case (mine was hot) and my action resolved the problem.
Domestic & General and Hotpoint were useless at attempting to fix this and the same problem with an FDW20 where they blamed the error on Rinse Aid and Salt use - this is rubbish.
I hope this helps you.
Regards
Paul
Paul, January 2008