Took my car in this morning when the check engine light turned on. Was told it was a misfire, and the dealer wanted more time with the car to drive and test it out. I've complained about the general shuttering I get once in a while at a stop light, where the car feels like it's about to die but doesn't. Yesterday afternoon, I went to move my car into the garage. It was cold from sitting all day. It shuttered a bit, revved at 1,500 rpm. I just drove it in and parked it. This morning, did the same thing, only this time the check engine light came on.
Just got a phone call from the dealer. They say it's a carbon buildup and they are going to replace the pistons under warranty! I've had three IS250s. Each one had this shutter issue. I'm glad that I had the dealer put into my file the complaints I've had about the shuttering issue, despite their not being able to find any problem. I have 69,000 miles on my car, and I believe this issue was covered under warranty because of that.
Regardless, I am happy at this point that Lexus is taking care of the issue!!!!!!