Focus Mk3.5 DAB problem - error B1D55:15-2F Antenna #2

[redrabbit29]

Hello,

My DAB on my 2014 Focus 1.0 EcoBoost (2015.25MY Mk3.5, SYNC 2) - keeps cutting out, every 10 seconds it displays a "Station Not Found" error.

The Problem

• DAB repeatedly cuts out, often around every 10 seconds. This is after scanning and it's not related to the location.
• It displays “Station not found”, then may come back briefly before dropping again.
• FM works normally.
• Problem started immediately after the car had some engine/camshaft work carried out, although the garage says nothing they did was related to the radio/aerial.

FORScan

The ACM consistently reports:

• B1D55:15-2F – Antenna #2
• Circuit Short To Battery Or Open
• DTC Present at Time of Request

If I clear the code, it immediately returns.

What I've checked

• Removed the ACM and inspected it - looks fine, with no water damage or problems I can see.
• Replaced the ACM with a "brand new" (i.e. working) one and still the same error
• Inspected the roof aerial/base and connections - this was brief as I wasn't sure what I was lookign for. It all looked fine, very clean, no major issues
• Removed the tailgate trim and inspected the rear-window aerial amplifier (7CP1-18C847-CA / Fuba 30761696) and glass connection. Everything appears connected and undamaged.

What next?

So I'm now looking for advice on where to go next with the aerial/wiring side of the diagnosis, particularly what B1D55 “Antenna #2” actually corresponds to on this specific Mk3.5/SYNC 2 setup.

Has anyone had the same fault or know the best next component/circuit to test?

Forscan screenshot