I. Hear clicking noise from relay box on my BMW Z3 when engine is switched off off
hyjacker and oP both./
no year told, wow.
no country told
in the USA we have EVAP 3, systems test s
that even run as we sleep.! but does not repeat, key off. 1 time yes. key off. or delayed as the PCM waits for fuel to cool off.
(tank pressure tests it does,by law here USA)
if really curios find the source of the noise
under hood, under dash, under at gas tank(evap parts)
use long cardboard tub to an ear and find it. this is not hard to do.
find the source first then ask why it makes noise.
and get real answers, 3000 parts on car gee.
or pull fuses when it makes noise.
you didnt say aftermarket ALARMS with shake switch horror !
or other wild car hacks , remote starter man killler.
key off , noise is very small list of things key off .
we are deaf here so all I can say is learn to find noise even making home made tools or a $5 mech stethoscope. (I have and electronics one with 4 microphones
your noise is easy find,car parked, be happy it does not happen only moving car, those can be dangerous to find, lacking my tools
or ask tech to find the noise.
what else is there?, nada
got other hacks, like REMOTE START BOX>
we can't guess why any car or machine makes noise!!! ever.
only how to do the tests. what stops you, IDK.