Check Engine Light - Bad Cats??
Thread Starter
Pro
Joined: Feb 2005
Posts: 564
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From: Saint George Utah
Check Engine Light - Bad Cats??
About 6 months ago I installed a Dynamax set of headers, X pipe and high flow cats. Recently the check engine light came on. Diagnosis was two faulty air induction check valves located under the intake manifold. I gather these take in exhaust gas from the headers. Big bucks to replace.
Three weeks later the check engine light is on again. Dealer says the codes are 0420 and 0430, indicating the cats are not functioning.
Does anyone have any similiar experiences and proposed solutions?
I suppose if the cats really are bad they can be returned under warranty.
Three weeks later the check engine light is on again. Dealer says the codes are 0420 and 0430, indicating the cats are not functioning.
Does anyone have any similiar experiences and proposed solutions?
I suppose if the cats really are bad they can be returned under warranty.
Former Vendor
Joined: Nov 2005
Posts: 11,792
Likes: 255
From: Ossining New York
St. Jude Donor '07-'08-'09-'10-'12-'13-'14
all cats are not created equal.......
Originally Posted by TroyPyles
About 6 months ago I installed a Dynamax set of headers, X pipe and high flow cats. Recently the check engine light came on. Diagnosis was two faulty air induction check valves located under the intake manifold. I gather these take in exhaust gas from the headers. Big bucks to replace.
Three weeks later the check engine light is on again. Dealer says the codes are 0420 and 0430, indicating the cats are not functioning.
Does anyone have any similiar experiences and proposed solutions?
I suppose if the cats really are bad they can be returned under warranty.
Three weeks later the check engine light is on again. Dealer says the codes are 0420 and 0430, indicating the cats are not functioning.
Does anyone have any similiar experiences and proposed solutions?
I suppose if the cats really are bad they can be returned under warranty.
What happens with hi-flow cats is that the exhaust sometimes flows too quickly through the cat for it to chemically convert the "bad" exhaust into good clean exhaust so the second O2 thinks the cats are not working cause there is not enough of a net change in the exhaust gasses from one o2 to the other..
Also, what happens is the O2's see so much airflow with hi-flow cats that they sometimes "cool off" and the heater in the O2 cannot maintain temp so the O2 feedback to the pcm slows down and is no longer accurate.
Hope this helps....
Chuck CoW
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Joined: Feb 2005
Posts: 564
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From: Saint George Utah
That's very informative.
Any idea why it may have happened so long after the install or what to do about it? Can I just turn off the light and see if it happens again? If so how is that done?
Any idea why it may have happened so long after the install or what to do about it? Can I just turn off the light and see if it happens again? If so how is that done?
Former Vendor
Joined: Nov 2005
Posts: 11,792
Likes: 255
From: Ossining New York
St. Jude Donor '07-'08-'09-'10-'12-'13-'14
winter summer fall spring.......
Originally Posted by TroyPyles
That's very informative.
Any idea why it may have happened so long after the install or what to do about it? Can I just turn off the light and see if it happens again? If so how is that done?
Any idea why it may have happened so long after the install or what to do about it? Can I just turn off the light and see if it happens again? If so how is that done?
number 1: when was it tuned? install of parts...? warmer weather?...now it is cold and air density is very much different.....by as much as 80 degrees....right? everything is colder...cats..o2s....cats don't work untill they are hot....neither do O2's....
number 2: lots of guys tune for NOW....but, some customers use their cars year round and the tune needs to be correct for year round use....if it kicks codes or changes how it runs significantly from winter to summer....it's not tuned right.....
if it wasn't tuned....it needs to be....
Hope this helps....
Chuck CoW
Le Mans Master
Joined: Sep 2003
Posts: 6,276
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From: Farmington CT
Cruise-In VII Veteran
Originally Posted by TroyPyles
About 6 months ago I installed a Dynamax set of headers, X pipe and high flow cats. Recently the check engine light came on. Diagnosis was two faulty air induction check valves located under the intake manifold. I gather these take in exhaust gas from the headers. Big bucks to replace.
Three weeks later the check engine light is on again. Dealer says the codes are 0420 and 0430, indicating the cats are not functioning.
Does anyone have any similiar experiences and proposed solutions?
I suppose if the cats really are bad they can be returned under warranty.
Three weeks later the check engine light is on again. Dealer says the codes are 0420 and 0430, indicating the cats are not functioning.
Does anyone have any similiar experiences and proposed solutions?
I suppose if the cats really are bad they can be returned under warranty.
the 0420/30 codes are common w/ long tubes, o2 sims or tuning will eliminate these, often times individuals will install the rear o2 connectors incorrectly, the left wire goes to the right o2 sensor and vice versa
Instructor
Joined: Feb 2005
Posts: 228
Likes: 3
From: Va Beach VA
I got a set of those headers used and got those codes within a week. Just means the PCM doesnt like the fore/aft sensor comparision. Wont hurt the car and the rears can be edited out when you get tuned 
Thread Starter
Pro
Joined: Feb 2005
Posts: 564
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From: Saint George Utah
Car was not tuned after the exhaust install. I let the PCM figure it out. Worked fine for the first 6 months. Definately colder now though.
I'd like to turn the check engine light out to see if it will come on again or if the problem may have solved itself - as many other bugs on this car seem to ahve over the years. How do I turn it off?
I'd like to turn the check engine light out to see if it will come on again or if the problem may have solved itself - as many other bugs on this car seem to ahve over the years. How do I turn it off?
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I had a similar problem when I had the headers installed.
I did absolutely nothing but reset the codes every time they showed up.
I was initially getting codes once or twice a week then once every two weeks after about three months and they were gone.
I believe there is a coating on the inside of the headers that burns off over time.
Not sure if your problem is the same but this has been my experience.
I did absolutely nothing but reset the codes every time they showed up.
I was initially getting codes once or twice a week then once every two weeks after about three months and they were gone.
I believe there is a coating on the inside of the headers that burns off over time.
Not sure if your problem is the same but this has been my experience.
Instructor
Joined: Feb 2005
Posts: 228
Likes: 3
From: Va Beach VA
I'd like to turn the check engine light out to see if it will come on again or if the problem may have solved itself - as many other bugs on this car seem to ahve over the years. How do I turn it off?
Hope this is what you were looking for