Same Problem, Different Model
My 2007 IS350 just encountered this problem as well, so I figured I would post here to add to the disgruntled customers. I have around 47,000 miles on this car, so this is pretty disappointing. What makes it all worse is a dealership replaced this unit WITHOUT NEEDING TO a year and a half ago. I am going to call this dealership and ask them to pay the 800 dollar cost (strange that my bill is lower than the average as I am taking it to a Lexus Dealership.)
We'll see if Lexus takes responsibility for this considering my unique situation, but I certainly think an essential piece of the car breaking after 4-8 years of limited use is absolute crap no matter how you view this. If Lexus wants to keep their reputation in tact, they should pay for repairs to obviously shoddy technology they placed in their vehicles.
We pay a premium for Lexus vehicles, so we should receive premium piece of mind and premium service. This is the least they can do when their competitor, BMW, pays for all service (even oil changes) on their cars. We'll see how my situation ends up being resolved... I will be fighting this, though.