You could always look in the manual
https://www.manualslib.com/download/602158/Aeg-Electrolux-Esl-6180.html
Page 14
Its not very helpful though.
Did a search for "electrolux AL7" - which YOU could have done and found these, which MAY be some help:
http://www.ukwhitegoods.co.uk/forumsphpbb3/zanussi-de6965-error-code-al7-t72738.html
https://www.justanswer.com/uk-appliance/76zny-aeg-oko-favorit-64800-showing-al7-within-few-minutes.html
poi
November 2017