Question

im getting both codes p0420 and p0430 what could be my problem and i had a mechanic check and he said everything was coming up good with all the readyness test were showing good what can it be????

Answer 1

Unfortunately your Xterra may have bad catalytic converters.

The catalytic converters are cover under the Long Term Federal Emissions warranty which is 96 months and 80,000 miles. If your Xterra is below that, the catalytic converters should be cover under warranty.