P0420, P0430 Catalyst Efficiency
Code P0420 indicates that the exhaust gas exiting the catalytic converter is too similar to the exhaust gas entering the converter. A faulty or overloaded converter due to an unbalanced air/fuel mixture can cause this condition.

Anyone have this problem with their G before? What could it be?

My G has 90k miles on it, could it be the cats?

It says it may also be 02 sensors, or a few different other issues, but mainly it seems to be either the Cats or the sensors...

Thanks!

 

do u have any smoking or power loss

 

nope, also when I use the scanner it actually says the o2 sensors are fine....

 

well ur getting hfc right maybe that will fix it

 

ya but not for like a couple months

 

just google the code that brings up a lot stuff

 

ya ive been reading up a lot about it just nothing really clear is out there, even on here theres only a few threads talking about it and not really informative

hey do you know how long stock cats should last for?

 

it depends on how u drive and the mods u have, how hard u drive is a big part too

my guess is they should go for at least a 100,000 if not more

 

if the front and rear sensors are reading the same, the cat is bad.

 

Dunno how to check the readings for front and rear sensors and Im guessing i dont have the tools to...

BUT, my scanner does check the sensors and it says the o2 sensors pass fine with no issues

 

thats the one, o2sensor 1 and o2sensor 2. compare the voltage high's and voltage lows

 

the scanner doesnt give me the readings for the o2 sensors, just weather it passes or fails

 

i got the same thing today bro. same code. i have 300 cell HFC. havent had them for more than a year. car has 40k. i dont know what 2 do either. sucks

 

found this bro. im gana try it todayhttp://www.civicforums.com/forums/7-honda-civic-diys-civic-tech-chat/329421-diy-o2-sensor-bypass-spark-plug-non-fouler-trick-installation-w-pics.html

 

^ let me know if that works....i just got Megan TPs and got the check engine light...