I have a 98 CLK320. The FM radio does something odd. From listening to it,it seems to pop in and out of 'stereo' mode, even though the indicator always reads 'stereo' on the display. CD and Tape are fine, just FM is a problem. Of course the Dealer cannot reproduce it and MB is resisting authorizing a replacement. Any suggestions?

Usually when an FM radio alternates between stereo and mono reception it means that the receiver is not picking up a strong enough signal to deliver a noise free stereo output.
It will automatically switch to mono operation.
Are you having this same problem with all FM stations? The newer Mercedes with the hidden antennas do not get the reception that the older models with external antennas did. Try tuning in a local FM station that you know has a strong signal. If you still have the problem then I would have the antenna and it's connection to the radio checked and possibly the radio itself.

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'98 E430
MBCA-Peachtree

Thanks for the advice, Bill.

The problem seems to happen even with strong local stations. The dealer already checked the antenna connections which are OK...and I haven't had any problems regarding reception of stations. They also pulled the control unit for bench testing...which was OK. I just notice that the stereo effect comes and goes while I'm driving (yet the 'stereo' indicator always stays on...which is odd). I think it's a calibration problem within the tuner. I tried the same stations on the same roads with my Toyota, and they play fine. I asked the dealer to temporarily swap it with another one...just to see if it works differently, but he says he needs additional approval for that...which was three weeks ago.

I also have a CLK and have the same problem pulling in strong local FM stations here in the L.A. area. I've concluded that this has nothing to do with the head unit--even my cheap $100.00 stereo in my BMW gets better reception--and has everything to do with the hidden antenna. A Japanese manufacturer had the same problem a few years back when they put a hidden antenna in one of their coupe models.