I have codes "P0420, P0430, and P1446." Where do I begin to correct this problem?

Question

What could be causing the real problem with this mixture of codes?

Answer 1

P0420 Catalyst below threshold bank 1

P0430 Catalsyt below  threshold bank 2

P1446 Evaporative Vac solenoid circuit malfunction

I see alot of catalyst lean bank on Nissan Xterra,If the sparkplugs are worn you code up a lean bank code and also a catalyst code, but you have 2 catalytic codes.These are expensive,and i belive you are only 5 % worn,A lean bank can also be caused by a vacuum leak So fix P1446 There is a TSB on your situation,P1446 may be the root cause of the catalytic code. P1446 is about the EVAP vent control is stuck open or will not seal when operated/closed Refernce NTB07-058 , classification ECO7 -006 , After you handle P1446 and it is satisfied do a fuel injection service, This may help restore the catalytic, Ive done this and had great success reviving catalytics.