P0420 and P0430. Should I replace all O2 sensors?

[jonnydclark]

I have a 2001 Maxima SE 5spd. I just fixed some wire harness issues, replaced IACV and MAF and t-stat to get it to run right. At this point it runs awesome but the P0420 and P0430 code comes on before I compete all the monitors. I have an OBDpro reader and it does appear that the downstream O2 sensors jump around almost the same as the upstream sensors.

Would running 87 octane cause this? I always run 87 octane but filled up tonight with 93.

Would running rich for some time (T-stat stuck open caused high rich idle, IACV not seen by computer due to wire issue....2000 rpm idle) kill O2 sensors before the Cats?

Can the Cats be bad and still have great performance?

Any help would be appreciated.

Jon

[NutriaforBreakfast]

My guess is you need a new O2 sensor (the last onetoward the end of the tailpipe). I fixed those codesby replacing mine

[jonnydclark]

Anyone have experience with the $29 generic sensors? Are they similar just without the wire harness or are they no good?

[NutriaforBreakfast]

All I know if the O2 sensors have to be "3 wire"

[mndiep]

jonnydclark did you resolve this problem? What was the solution?