P0420 2002 Nissan Altima Sedan -

Question

I have a P0420 code and will replace the catalyic converter.
Can I get away without replocin the O2 sensor?
Should I try replacing the O2 sensor first?
Any past experince with this code, that turned out not to be the CConverter?

Answer 1

If you have serviced your car in a timely manner, if the spark plugs have been replaced, ignition timing is good, if you always use 91 octane gas and there is a 5% chance that the oxygen sensor is bad, if you skips services and not do them on time and use low octane gas which in the long run destory the catalytic converter most likey your catalytic converter is bad.

 

possible causes: 

Three way catalyst (Manifold)

Exhaust tube

Intake air leaks

Fuel injectors

Fuel injector leaks

Spark plug

 Improper ignition timing