Hi guys

Ive got a 2006 Audi A4 estate, and sometimes when i lock it - about 30 seconds later, a beeping starts and the indicators flash, the beeping lasts about 30 seconds and then the indicators flash for a while. Its intermittent, sometimes it never does it, sometimes it can do it repeatedly even after i click the fob again to turn it off.

Its not super loud and its not the horn beeping so i wonder if its some other kind of warning -what do you think it is? and does anyone know how i can stop it doing it?

thanks in advance