I have a 2003 L-tuned IS300. Its been good to me, but this summer its actually been a a series of unfortunate things happening to it. First the Transmission gave on me along with the clutch at only 22k miles. Then the Water Pump needed to be replaced. On Labor Day some non-driver rear ended my car. Now I have my check engine light on and my traction control light flicks on and off when I'm driving. My mods are SRT- Intake, HP Headers with high flow cat, exhaust side cam gear, and a crank pulley. When I had my Headers put in over a year ago it came with an O2 simulator and I put that in. I took it to Lexus and there saying its coming from the exhaust, but since I've modified it they can't do anything to it; therefore I order another O2 Simulator just in case this one went bad. I have a feeling its something else because the Trac control light is flicking on and off too, ever since when does that go on with a Check Engine light? If anybodies delt with a check engine light issuse along with a trac control light flicking on and off PLEASE feel free to give me some input. I'll let keep you guys updated when I get problem resolved. Thanks and hope to hear from guys.