2003 Lexus GS 430 Catalytic converter

This vehicle has two catalysts one for each side of the engine or in other words one catalyst per four cylinders.
Catalyst failure it a result of a overheating (melting) issue or the catalyst material inside has been contaminated preventing the unburned fuel in the exhaust to burn increasing emissions. A faulty oxygen sensor can also cause a false catalyst failure, meaning if one of the oxygen (or in this case a air/fuel sensor) sensor is bad sending incorrect data to the vehicle's computer triggering the check engine light for a catalyst fault code.

Cleaning almost never works due to the fact catalyst operate at high temperatures (around 1200F). This high temp burns anything coming through the catalyst causing any contaminates to stick to the reactive elements inside. This causes a baked on coating effect.

Blanking out the check engine light will only make the light go away. The fault is still detected by the vehicle's computer and will be stored. Any emissions test will check for any fault codes and fail the emissions test because the vehicle has detected a emissions failure.

Hope this answers your questions