P430 code O2 sensors show no difference

[Peanut74]

My Ex gave me a P430 (catalyst system efficiency below threshold - bank 2) when my friend pulled the codes. He put his scanner in diagonstic and the bank 1 and 2 O2 sensor had the same reading. The truck runs fine and does not idle rough or give any signs of a problem.

About a month ago i got an P420(?) where it the o2 sensor was bad on bank 2. My question is should I start by replacing the o2 sensors since they have never been replaced or is there a way to troubleshoot it?

Thanks in advance. This site has helped me out a bunch.

 

[bobflood]

My Ex gave me a P430 (catalyst system efficiency below threshold - bank 2) when my friend pulled the codes. He put his scanner in diagonstic and the bank 1 and 2 O2 sensor had the same reading. The truck runs fine and does not idle rough or give any signs of a problem.

About a month ago i got an P420(?) where it the o2 sensor was bad on bank 2. My question is should I start by replacing the o2 sensors since they have never been replaced or is there a way to troubleshoot it?

Thanks in advance. This site has helped me out a bunch.

P0420 indicates the same thing as P0430, just for bank 1 instead of bank 2; so you probably got a different code a month ago if it was a bank 2 code. It would be good if you could figure out which code you got last time, as the O2sensor codes usually indicate "S(ensor) 1" or "S(ensor) 2" - this would tell you which Bank 2 sensor to replace.
Also, was your friend comparing "Bank 1" and "Bank 2" sensor readings, or was he comparing "S1 and "S2" readings for the same bank?? Seeing the same readings on S1 and S2 for the same bank is one of the things that would trigger a "catylst system efficency" code.