if you dont get an answer till monday, i'll check it up in class with teh scan tool. if u dont get an answer by sunday night, pm me n i'll get it to u by 7 pm. monday evening(got class all day).

 

get knowledged before you start replacing and throwing parts at a car...

50% of the time and o2 sensor code isn't ur o2 sensor, unless the scantool shows u that its not switching from rich to lean and not functioning at all...

dealership isn't trying to get money off of u, its called diagnostics fees, they want u to bring it in, and have a tech scan ur dtc's and see whats going on and give u his peice of mind, u can findout what a code means but that doesnt show you anything.

ur o2 dtc coming on may be juswt an indicator that ur running very rich and out of the wideband specs... theres a reason for that not just the o2, the o2 is just a sensor... reads the exhaust coming thru, so u may have other problems.. did they give u a sheet with ur inspection on emissions showing u the co2s and cos and hcs etc? that can be a good indicator..

ur vehicle is fairly new and its not common for ur o2 sensor to be shot, if u dont have access to a scan tool, then take it somewhere who does, im pretty sur ea generic scan tool can tell u what a p0420 is... and im sure that code is on this website somewher eu just gotta search...

good luck

 

Check the CEL following the steps in our article: CEL article

 

http://www.ff-squad.com/ecu/tech.ecu.codes-p.htm


fellas, P code from a scanner is different from the CEL code (or as they say in the biz Maintenance Indicator Light = MIL) method.

P0420 = MIL (CEL) Code 67 = Catalyst System Efficiency Below Threshold

Your cat's ****ed.

 

update:

p0420 (67) - Catalyst system Efficiency Below Threshold malfunctioning or defective catalyst system

1. Three way Catalytic convereter (TWC) deteropration
2. Exhaust system leakag
3. o2 Sensor not functioning properly

its the 3way cat most likely for that code, and ur efficiency is how much co2 ur have, the mure co2 the BETTER, and the less nox the better... so if u look at ur sheet/print-out u can see what's up.

u can also smell ur cat not working(rotten egg), u can hear exhaust leaks)

if u have a leak b4 the cat, ur efficiency goes down, so that could throw that code...

to see if ur bank2 downstream o2sensor is working, u would have to look at a scantool and watch the o2 sensor while ur car is running (at op temp) and see if its switching, the second one is a bit slower than the 1st (natural).

so hope that helps a bit.

 

Or you can take it to a local autozone and they will do a check engine light for free. I had my mine come on and they checked it with a scan tool.

 

67Catalyst System error....so since my car may just be running to rich what can i do to stop it from running rich. do i need to fuel tune. or if i put all stock equiptment back on will the code clear.

thanks for the help. and i do realize it might not just be the 02 sensor if it is an o2 sensor code.

i don't have an exhaust leak. and i have taken the cat off before...all looked normal and i showed it to my neighbor and he said he was 99% sure that the cat wasn't my problem. he has been an auto mechanic for 30 years now. so he knows what he is doing. also there isn't a rotten egg smell comi from the exhaust.

 

ok ur fell off a bit...

catalyst efficiency problem.. aka ur cat isn't doing its job.

you can confirm its efficiency by looking at the printout from when u got ur emissions inspection

co2 would go down (efficiency indicator)
if there is an exhaust leak, o2 would go up..
nox (since its ur threeway cat) would go up

if it was running rich, co would go up
lean o2 would go up
and misfire (hc)'s would go up...

so basically i dont think u need to **** with ur fuel mapping lol.. i think u might need a new cat b/c its not doing its job anymore and u can confirm that with ur printout.

and sorry that ur a college student (whose usually broke).. but u may have to buy a new cat..

call some junkyards?? lol whatever u gotta do, or toss the guy 50 bucks to pass u.

 

ok.. so ur cat could be OK. (confirm that with ur 5 gas analysis).

now all u gotta do is look at a scan tool and find ur o2 sensor and watch the numbers (voltage) switching.

it shud bge like .12v, .35v, .85v, back down the .10v etc etc

rich/lean/rich/lean/rich/lean.. if its not working too good, u may need an o2 sensor then,


remember ur o2 sensor tells the computer if the cat is doing its job, thats basically what its there fore, so if the o2 sensor os ****ed up then its telling ur computer some bullshit, and the computer tells the light to come on and throws a funky code that ur cat isnt operating wher ur o2 sensor is just bullshitting it (that make sense? lol)

but dont replace untill u confirm, scantool, possibly the DEALER (ahhh) and have someone who just doesnt throw parts at a car and hopes it fixes the problem, have them actually watch the o2 and not just read the DTC code.

 

HEY guys i just got a brand new cat for 400.00 and a brand new o2 sensor for it and a few weeks later the same code came up P0420 cat system efficiency below threshold bank no. 1. I am confused because everyone says its the cat.

CAN anyone help?

 

Is that front or rear O2 sensor that you replaced? Most times when replacing the cat, its beneficial to replace the front O2 sensor along with the cat. Replacing the rear is also a good recommendation.

Reason being is because the front O2 controls fuel. It may most likely be due to a faulty front O2 sensor that caused the cat to go bad. Therefore making the rear one go bad as well.

 

well when i replaced my cat i also replaced the 02 sensor that goes on the cat and then the check light went off. took it to smog i passed. 2 days later i got this code and people on here are saying its the cat. i think it might be the sensor thats on the header.... you think so?

 

Hey dark gsr, just wondering, I saw you said something about putting your stock parts back in. Do you have any mods done to the engine, exhaust or fuel system??

 

It will usually tell you either sensor 1 or 2. I know it did for me. 1 being on the header.

 

This would be the postcat sensor or the cat itself. A code for the precat sensor wouldn't likely mention a catalyst problem because its job is to advise the engine on air/fuel ratio. P0420 means that either the postcat sensor is producing no signal or the signal is too close to the precat signal (and therefore that the catalyst isn't catalyzing). If it's your new $400 catalytic converter, you should be under some kind of warranty.

 

Replacing the fuel filter got rid of the P0420 code in my RSX-S.