Citroen C8 Radio Antenna Issue

Sounds familiar. I had similar problems with my old Opel Astra, a total pain. The FM signal was weak. I'd check the antenna ground first, that's what it was with my car. Is it just FM, or DAB as well? Have you checked the physical connection of the antenna cable to the head unit? Poor signal can be caused by various things.

It's both FM and DAB that are affected. I haven't checked the physical connection yet, I'll try to locate it in the dashboard. Where should I check the antenna ground? Is it easy to get to?

On my Astra, the antenna ground was under the antenna base on the roof. But accessing it was tricky, I had to partially remove the headliner inside. If you're not comfortable doing that, or can't find it, I'd suggest taking it to a workshop. Radio interference can be a pain to troubleshoot without the right tools.

I took it to a local mechanic, and they confirmed the antenna was defective. Replacing it cost me 255€, and the radio is now working perfectly again. The error message is gone as well. It appears that this solved all problems.