what could cause my catalytic to go bad on 1997 Lexus LS400

code PO431 PO420 PO430

Asked by for the 1997 Lexus LS400
2 answers
old age or fuel issues.
age and fuel issues. today's fuel uses more ethanol. residues cause clog's in fuel system's and exhaust system's. try fuel additive(specificly ethanol treatment).