Hi mate
I had an is200, and had the exact same fault as yours. After a month or so, the trc etc light started flashing again, so this time I took it into lexus dealers. They put a computer onto it, and there were no faults stored, but I didn't know this before I bought the car, but the technician there told me a lot of is200 have a fault on the ecu, and the problem with mine was the ecu. So when the light eventually stopped, I sold the car. But just wanted to let you know, that it could be a fault with the ecu, if it did start flashing again. And a new ecu is not cheap. If you get a secondhand one, you'd have to buy all the locks aswell, I couldn't afford all that, plus you don't know how long a secondhand one will last.