Hi, I've just experienced the same problem today with my 2006 is250. Reversing out of a parking space in work, the power steering became completely unresponsive, no warning lights on the dash, no other problems with the car. Have to get it towed to the lexus garage tomorrow.
I was just wondering @Exdee what the outcome was with your car? Did you find out what was the cause of your power steering problems?
I noticed a couple of people mentioning tyre pressure, can this cause a power steering failure? The reason I ask is that I was using an electronic tyre pump at a service station two days ago and it malfunctioned and I'm pretty sure my tyre pressure is low in the front tyres. I was going to pump them at another station but just never got around to it!
One last question, if it is a problem with the electric motor, does anyone have any idea how much I might be looking at to get it fixed?
Thanks.