How do I know if my catalytic converter is bad or ok? - Honda-Tech

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How do I know if my catalytic converter is bad or ok?

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Old 11-05-2007, 09:30 AM   #1
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Default How do I know if my catalytic converter is bad or ok?

I recently made a purchase on a Apexi WS2 cat-back system, I just want to know if I should change the cat too, I dont know if its bad or not, but one of my friend said that if the cat is bad, then the o2 sensor is bad, is this correct? I'm not getting any CEL or hearing ratting sound. Also, is it necessary to change to a test pipe or some other cat? thank you.
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Old 11-05-2007, 09:45 AM   #2
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Default Re: How do I know if my catalytic converter is bad or ok? (ShinotakuX)

u can change the cat to a test pipe but it will be loud but better air flow..but illegal...if your cat converter does not rattle..or make any noise..then it is ok
and ws2 is a good cat back i am actually thinking about getting one too
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Old 11-05-2007, 09:48 AM   #3
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Default Re: How do I know if my catalytic converter is bad or ok? (crazyguy)

what year is your car...that makes a difference..older civics dont have the 2ndary rear o2 sensor...but to answer your question, if your cat is bad, you will lose alot of power and flow...best way to tell if its losing flow..start the car, hit the gas a couple times and feel the tail pipe real quick, there should be a good amount of pressure coming out - but yea, if your cat is really bad...youll actually hear exhaust come out of the cat..the springs stretch out almost as a fail safe so that exhaust doesnt go back into the motor...it sucks..but its a cheap easy fix


PS: dont use a test pipe..if anything at all get a high flow cat...but check your cat the way i said, if you have to replace it..get an oem cat..a high flow cat (and even a test pipe) doesn't give you much of anything except noise and smell. stick with an OEM cat
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Old 11-05-2007, 09:50 AM   #4
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Default Re: How do I know if my catalytic converter is bad or ok? (Probot)

its a 96 honda civic ex aka ej8.
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Old 11-05-2007, 09:53 AM   #5
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Default Re: How do I know if my catalytic converter is bad or ok? (ShinotakuX)

yea, you have the 2ndary sensor - just check for flow like i described, but most of the time, if your cat is going bad the sensor will throw a CEL

or if you are really worried about..just pick up a new oem replacement one from an auto parts store..they are cheap
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Old 11-05-2007, 10:25 AM   #6
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Default Re: How do I know if my catalytic converter is bad or ok? (ShinotakuX)

Quote:
Originally Posted by ShinotakuX
its a 96 honda civic ex aka ej8.
yeah ej or ek has secondary o2 sensor on the cat converter...and the aftermarket test pipe will have o2 bunk on it too..
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Old 11-05-2007, 11:00 AM   #7
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Default Re: How do I know if my catalytic converter is bad or ok? (ShinotakuX)

Your car has a secondary O2 sensor after the cat(Or on it)

You should get a cel if the cat is bad. Or like your friend said you have a bad o2 sensor on or after the cat, it would throw a code still. The secondary O2 sensors only job is to keep an eye on the cat.

In CA you will have to do smog checks so a cat is required to pass I suggest an OEM one if you do need to replace it.

If no cel then you are ok and the cat is too.
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Old 11-05-2007, 11:27 AM   #8
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Default Re: How do I know if my catalytic converter is bad or ok? (ShinotakuX)

yeah, if the cats bad you'll throw a p0420 i think. either way it's more often the cat bad not the O2 on these models. in my experience that is...
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Old 11-05-2007, 11:36 AM   #9
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Default Re: How do I know if my catalytic converter is bad or ok? (hondamark35)

Are you guys sure a High Flow Cat will still pass inspection - NJ?

EDIT: How much of a sound differnece between the high flow and a test pipe. x10000 lol
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Old 11-05-2007, 01:25 PM   #10
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Default Re: How do I know if my catalytic converter is bad or ok? (HondamanXxX)

Quote:
Originally Posted by HondamanXxX
Are you guys sure a High Flow Cat will still pass inspection - NJ?
It depends upon the cat.

Quote:
Originally Posted by HondamanXxX
EDIT: How much of a sound differnece between the high flow and a test pipe. x10000 lol
Most test pipes normally result in a "raspy" exhaust note, which is avoided when using a true high-flow cat.
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02, back, bad, cat, catalytic, converter, converters, flow, good, high, honda, inspection, nj, p0420, replace, smog

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