P0420 2003 Nissan Altima Sedan -

Question

-List item l have this codes on my nissan altima 03 p0420 and p0021 are know whats this..maybe the catalytic

Answer 1

p0021 could be caused by dirty or low oil since the Intake valve timing control solenoid valve uses oil flow to control timing, dirty oil can cause the valve to stuck open or close. Before replacing the valve, change engine oil and filter and reset engine code (you can also do an engine oil flush before puting in new oil)

P0420 is most likely a bad catalytic converter but try to fix the other issue first.