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400H bad FM signal

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Seems my 400H radio signal has 'dropped away'. I now find it hard to even get the main stations like Radio 2. Has anyone else experienced this? are there any common issues with connections/amps or similar? (I have the Mark Levinson system)

Thank you.

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Never had that problem but I suspect either the antenna itself or the amplifier has gone bad. The antenna should unscrew from the base and can be replaced with something generic, or official part 86309-48040. I'd try something generic from eBay/amazon for a few £££ just to help with the diagnosis.

If the amplifier has gone bad (which is housed in the base of the antenna on the roof) then that is pain to replace as it is bolted in from under the roof lining. The official way to take off the roof lining is some 50+ step process and involved removing a lot of the internal trim. I believe some people have managed to pull down the lining without removing trim and getting enough room to get a spanner in there - I've never tried so don't know how difficult that is, or how easy it could be to damage the lining.


Other possibilities are the cable that goes from the roof to the head unit, or the receiver in the head unit itself, but given the antenna/amplifier are outside and exposed to the elements that is where I would start.

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Thank you. Looks like I found the cause though. Stupid me. I added an FM transmitter via the lighter/charger socket, it works well to stream Spotify. However, I just found if I unplug it my FM signal comes back strong. So i guess while the FM transmitter is only using 1 specific empty frequency (which is 87.6, I programmed it into memory 6), it must be interfering too. Not a big deal to unplug it when not using streaming. Phew 🙂

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