P0420 Catalyst System Efficiency Below Threshold


i got a new high flow cat about a month ago when i installed my turbo kit. you guys think the o2 sensor is bad? the high flow cat is a magnaflow and the o2 sensor is position after the cat.

this seemed to happen after i installed my a/f guage i think. i redid the wiring, and about after an hour of driving, the CEL will return. so i don't know what it could be. the a/f guage works fine. i have no idea what else it could be.

 

you hooked your AF guage up to the upstream o2 correct?

It is possible that your cat moniter is bad but it also is possible that the high flow cat does not perform like the factory cat.

 

Well, I know on an My Evo VIII, Even with some types of highflow cats.. it'll still throw the 420 code. I just use the simple spark plug anti-fouler trick. to trick the rear o2 from gettin upset. I don't even run a cat on my car. It's just striaght 3" pipe from the turbo Back. If you wanna try the anti-fouler trick. just pm me or reply back. It's really simple and only take about 10mins to do... good luck..

-Chad-

 

normally 02 sensors dont set the p0420
the ecm logic for comparing front o2 signal to rear o2 signal doesnt like the amount of similarity between the two caused by your high flow cat.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by N20civicB18 &raquo;</TD></TR><TR><TD CLASS="quote">you hooked your AF guage up to the upstream o2 correct? </TD></TR></TABLE>

i hooked it up to the ecu white wire. C16 on obd2b - ph02s - promary heated 02, sensor-1

i used this diagram http://technet.ff-squad.com/wiring.obd2b.htm

how would i do this foul washer trick? i was thinking about replacing the o2 sensor to see if it just went bad or not. i have no other idea what it could be. i doubt the cat would go bad within a month when i barely and rarely push my car.

 

i was wondering if you guys think this will work

http://www.highrevmotorsports....=1108

casper's o2 simulator. it'll tell the ecu the cat is working fine, but wouldn't this give my a/f guage the wrong reading?

 

anyone know if a SIM would throw off my a/f guage?