[mrpingu]

Did you clear the error after connecting the antenna, is the error not present anymore?

The door handles have their own Fuse, that is fuse 13(7.5A)which is on the FEM module.
Double check the resistance on the aerial to make sure it’s not the aerial itself, you can do this at the FEM-side so you know the signal is reaching the FEM.

I’ts pin 9 and 27 on A173*9B


Edit: also a missing antenna would show the 'comfort access limited function' warning while a missing doorhandle would not give a message at all, there is no check on doorhandle function in place.
I am retrofitting comfort access on my F48 and I haven't connected all doorhandles and no message is popping up, but as soon as I disconnect one antenna I get the warning on the dash / infotainment system.