need help on a code. it was P0420 and it says "the catalyst system for bank 1 is below efficiency" or something like that. This is for another member on this board so I wont be able to answer what it feels like. he just called me from autozone and asked me to start a thread

 

The rear 02 sensor is not happy...If he has had a spell on race gas or changed his exhaust pipe, downpipe or cat the evo will place as a pending code and then throw a CEL...what has he modded?

 

he's probably running cat-less

 

i have an ultimate racing dp and hiflo cat. thanks brandon. Thats what i was thinking as well, but if u look at it closely... its 1st o2 sensor. not 2nd. I'm not sure why this is... am i correct that it is the first one?

 

Do you have Blow of valve installed? if you're venting (VTA) thats why.

 

PO420 code is catalytic efficiency is below threshold. bank 1 sensor 2 ( after cat )

meaning your catlytic converter is not filtering out enough CO and hrdrocarbons .
This code is normal if your running cat-less or a high flow cat ( some )

to get rid of it you have to invest in an O2 simulator.
This code will not affect performance.

 

I got this code after installing my UR cat.

Another fix is to use something to extend the rear O2 sensor so it doesn't stick into the pipe completely.
One way is to have a muffler shop weld a second bung onto the first.
What I did was to buy something called a spark plug anti-foul adapter.
You will need 18mm. You can find them at most auto parts stores.
Look on the "HELP" rack; you know, all those red packages with the unusual parts.
You will have to drill out the end with a 1/2" drill.
Screw the adapter into the pipe; screw the sensor into the adapter - you're done.
My code has never come back.

 

found the thread with great pics in it.

https://www.evolutionm.net/forums/sh...ad.php?t=62524

Look about 14 posts in.

Thanks again to Derekw.

 

thanks

 

Damn I got this code too ... I have the Random Tech 3" high flo cat

 

i hit it a few times with my wrench... put some liquid wrench and wd40 on there a for some reason just disappeared =P