2001 4.7 p0420

[dirt]

im getting code P0420 for cat efficiency below threshold bank 1, now i know my truck has 252k miles but in not sure if this is the original y pipe and since there is no sensors by the large 3rd cat im assuming my driver side precat is going bad. there is no other codes nd i just want to ask for any ideas on just getting a replacement y pipe for rock auto or just getting some walker universal cats from summit. or an other suggestions

[MadMike05]

change the first 02 sensor in your exhaust system, before the first cat. You might as well change all of them (25-35$) at autozone.

[got_torque]

Originally Posted by MadMike05

change the first 02 sensor in your exhaust system, before the first cat. You might as well change all of them (25-35$) at autozone.

Do this, then save money for 4 more OEM o2 sensors, since the Autozone ones will be bad in a week(if they last that long). Then you can go put a cat on it and fix your problem.

[dirt]

Well here is the confusing part I reset the light cause I hate the cel being on and then today I checked with the scan tool and it says catalyst sys monitor set and no light :/ could it of been a fluke?

[got_torque]

It will stay off until it runs that test again.

[Tech5]

Cat replacing time!!!!

It will come back just a matter of time ....Some times bad gas can kick the code , and a weak o2 sensor But As we have replaced more cats then O2 sensors being the problem I am going to say it will come back on soon and it will need a new cat ....