Owners of 2001-04 GS 430s and LS 430s, in addition to 2002-04 SC 430 models , may complain of an obnoxious chirping or squealing from the engine bay when the engine is initially started. One likely cause for the noise, says Lexus, is serp belt slippage at the pulleys, idlers or tensioner. A new-design accessory drive belt with a different rubber compound and superior rib design should help eliminate the noise immediately. The new belt goes by Part No. 90916-02586 for the GS and LS, 90916-02584 for the SC.