On my 2003 IS300, the tuning knob on the factory radio has gotten flaky - when you turn it, the FM frequency jumps all over rather than stepping up or down to the next or previous frequency. Has anyone else run across this? I'd appreciate some idea what it costs to get the radio fixed - trying to decide if Lexus will charge so much that I'd be better off just buying a new aftermarket radio.

I seen it where the potentiometer can be dirty and can cause issues kind of what your describing. I had an alpine radio that started doing that with the volume knob. I just blew it out with a can of compressed air and it fixed about 97.83425% of the problem The other thing you can do is get the part number off the side of the radio and call United Radio based out of New York. They do great work and I use them quite often.

Hope this helps!

I don't think that is a potentiometer - I think it's some kind of optical encoder or something similar that just generates a series of pulses as you turn it, where those pulses are received in the microcontroller and cause it to step through frequencies, setting values, etc. Regardless, I've also wondered if dust or some other contaminant could be the cause - but I'll bet the device is sealed.

Has anyone had one of these controls repaired? Any idea what it costs?

I have the same problem in my IS300. Hope you get it figured out so I can fix mine!