Need help with engine code

[GoldGalant [Reborn]]

I recently got the dreaded check engine light the code was P0421 Low catalytic threshold. What do I need to do?

[RedGalant2k1]

<div class='quotetop'>QUOTE(GoldGalant [Reborn)</div><div class='quotemain'>]I recently got the dreaded check engine light the code was P0421 Low catalytic threshold. What do I need to do?</div>

Fix it. Sounds like you may have a bad cat, or bad O2 sensors.

[jusmills]

I actually had the same code a couple of weeks ago along with a code for a misfire in 1 cylinder, I got my timing belt changed (needed it) and insulators/new wires and got the code cleared....haven't got the code again, so you might want to check other things too, in addition to obvious 02 sensors as mine were new when I first started getting the light.

[Kalamidad]

just had the same code...

possible three causes,

1) Bad Cat.

2) Large Vaccum Leak

3) Misfire

i happen to know i have a massive vaccum leak.

[Kalamidad]

Kev, did you ever replace your Cat? I got the same code today.