at the end of the cycle the panel flashes either F27 or P27, my eyes are not too good and I cannot quite distinguish

Deedee, January 2016

Google search for "Siemens S14-39 F27" throws up these results. Probably plenty mor eout there. You could try the same for "Siemens S14-39 P27" and see if you get anything.

http://www.fixya.com/search/p538400-siemens_wm14s794gb_front_load_washer/f27

http://www.fixya.com/support/t18367179-siemens_s14_39

http://www.howtomendit.com/answers.php?id=120527

Anon, January 2016