2000 Celica Check engine light

[honda900]

I have a code PO 420 on my 2000 celica. The code is catalyst below threshold (bank 1). Can anyone help me with this, or know what to replace to cure the problem. The car runs perfect with the light on or off, but it still bothers me. Thanks for the help. PM me with any ideas. Thanks

[TeeJay]

more than likely it is a bad o2 sensor giving you a wrong reading, or your catalytic converter is clogged up. this happened to me when i had an integra gsr and i just put a test pipe on and it went away. in your case u might wanna get it checked out by somebody cause u dont wanna spend money u dont need to. or there is this thing called an o2 simulator, basically u wire it from your o2 sensor to your ecu and it tells the ecu everything is ok, thus no check engine light...i would only recommend it if you use a test pipe or straight pipe though.

[honda900]

Thanks for the advice. I will see what I can do.