I been pondering over some recent fault codes of p0420 and p0430 codes found on my 2001 ls430. After some investigation I have a solution that can save everyone a lot of money. 1)The codes P0430 and p0420 indicate your catalytic converter efficeniency is reduced. This would lead one to believe that the catalytic converter needs to be replaced which can be a major expense since your ls430 has three catalytic converters. (two forward and one rear) . With a little investigation