One problem related to engine clicking and tapping noises has been reported for the 2003 Lexus SC430. The most recently reported issues are listed below.
The car failed to start six times in the first five months. It seems they have found the cause of that problem. However, the car continues to make clunking noise whenever it goes over a bump. Lexus tells me that is normal. I say it sounds like a 1973 Dodge I owned 30 years ago. The car also pulls to the right at low speeds. Again I'm told this is normal and is a result of the run flat tires. If so, they should use other tires. Parking brake light continues to come on intermittently. I have requested that this car be replaced repeatedly. Lexus has refused.