P0431 Code? - JeepForum.com
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post #1 of 43 Old 09-13-2011, 01:34 PM Thread Starter
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P0431 Code?

I just got a check engine light today for a P0431...does anyone know what this is and what needs to be done to fix it? I have an 05 TJ with 70K on it.

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post #2 of 43 Old 09-13-2011, 02:03 PM
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That's indicating a bad O2 sensor ("warm up catalyst below efficiency threshold"), but it's probably a bad catalytic converter, I think. If it's the cat, it's covered by 8/80 federal emissions warranty. Had the same problem, swapped out O2's twice, then had the cats replaced (one was hollow) by the dealer at no charge. Code's gone and fuel economy is up.


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Quote:
Originally Posted by Ron Paul
“Liberty is lost through complacency and a subservient mindset. When we accept or even welcome automobile checkpoints, random searches, mandatory identification cards, and paramilitary police in our streets, we have lost a vital part of our American heritage. America was born of protest, revolution, and mistrust of government. Subservient societies neither maintain nor deserve freedom for long.”
― Ron Paul
"Did you exchange your walk-on part in the war for a lead role in a cage?"
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post #3 of 43 Old 09-13-2011, 02:16 PM Thread Starter
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is there anyway for me to check if it is the cat?
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post #4 of 43 Old 09-13-2011, 02:17 PM Thread Starter
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also how do i know which one?
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post #5 of 43 Old 09-13-2011, 02:29 PM
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Quote:
Originally Posted by 2005-TJ View Post
is there anyway for me to check if it is the cat?
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also how do i know which one?
0431 is bank 2, which I think is the rear, but I can't swear to it. Some say you can hear if it's hollow or if the honey-comb is crumbled by tapping on it with a wrench or other "tapping devise". Worst case, unbolt it and have a look? I didn't even bother; after replacing the O2 a second time, I "knew" it was the cat and had the entire system between the manifolds and the muffler replaced when I replaced my cam.


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Quote:
Originally Posted by Ron Paul
“Liberty is lost through complacency and a subservient mindset. When we accept or even welcome automobile checkpoints, random searches, mandatory identification cards, and paramilitary police in our streets, we have lost a vital part of our American heritage. America was born of protest, revolution, and mistrust of government. Subservient societies neither maintain nor deserve freedom for long.”
― Ron Paul
"Did you exchange your walk-on part in the war for a lead role in a cage?"
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post #6 of 43 Old 09-13-2011, 02:38 PM Thread Starter
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The cat is covered under factory warranty for 8 yrs or 80k miles?
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post #7 of 43 Old 09-13-2011, 02:46 PM
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Quote:
Originally Posted by 2005-TJ
The cat is covered under factory warranty for 8 yrs or 80k miles?
Federal Law says so.


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Quote:
Originally Posted by Ron Paul
“Liberty is lost through complacency and a subservient mindset. When we accept or even welcome automobile checkpoints, random searches, mandatory identification cards, and paramilitary police in our streets, we have lost a vital part of our American heritage. America was born of protest, revolution, and mistrust of government. Subservient societies neither maintain nor deserve freedom for long.”
― Ron Paul
"Did you exchange your walk-on part in the war for a lead role in a cage?"
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post #8 of 43 Old 09-13-2011, 02:48 PM Thread Starter
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This might also explain my horrible fuel mileage...i only got 175 miles out of my last tank of gas
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post #9 of 43 Old 09-13-2011, 03:48 PM Thread Starter
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my buddy is coming over with a good snap-on scanner...is there a way for me to monitor and determine if it is the cat or an o2 sensor?
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post #10 of 43 Old 09-13-2011, 04:01 PM
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This might also explain my horrible fuel mileage...i only got 175 miles out of my last tank of gas
Yes, I could.

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my buddy is coming over with a good snap-on scanner...is there a way for me to monitor and determine if it is the cat or an o2 sensor?
Not that I'm aware of. There may be a way to meter the leads on the O2 sensors, but you'd have to search for that. I've seen it discussed here in Tech, but couldn't begin to tell you where, exactly.


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Quote:
Originally Posted by Ron Paul
“Liberty is lost through complacency and a subservient mindset. When we accept or even welcome automobile checkpoints, random searches, mandatory identification cards, and paramilitary police in our streets, we have lost a vital part of our American heritage. America was born of protest, revolution, and mistrust of government. Subservient societies neither maintain nor deserve freedom for long.”
― Ron Paul
"Did you exchange your walk-on part in the war for a lead role in a cage?"
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post #11 of 43 Old 09-13-2011, 04:27 PM Thread Starter
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not that i really know what i was looking at but all 4 sensors seemed to be in roughly the same range on the Snap-on Ethos scanner...i reset the CEL and it hasn't come back on yet.
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post #12 of 43 Old 09-13-2011, 04:38 PM
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not that i really know what i was looking at but all 4 sensors seemed to be in roughly the same range on the Snap-on Ethos scanner
That says to me that it's a cat.

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...i reset the CEL and it hasn't come back on yet.
I've got my fingers crossed for you, but give it about 60-75 miles of driving before you start holding your breath. With the recent drop in fuel economy you mentioned, I'd hedge my bets.


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Quote:
Originally Posted by Ron Paul
“Liberty is lost through complacency and a subservient mindset. When we accept or even welcome automobile checkpoints, random searches, mandatory identification cards, and paramilitary police in our streets, we have lost a vital part of our American heritage. America was born of protest, revolution, and mistrust of government. Subservient societies neither maintain nor deserve freedom for long.”
― Ron Paul
"Did you exchange your walk-on part in the war for a lead role in a cage?"
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post #13 of 43 Old 09-13-2011, 04:45 PM Thread Starter
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thanks for your help
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post #14 of 43 Old 09-13-2011, 06:15 PM
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P0431 is Bank 2 sensor 2. That is the last three cylinders before the firewall and the O2 below the cat.
1) If you pull the O2 and it looks flattened on one side your cat is on it's way out. Being all 4 O2's are switching the same the front three cylinders may be bad as well.
2) You could have a exhaust leak post the first O2.
3) Bad O2 sensor.

Since you reset the CEL it may take 4 days to come back.

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post #15 of 43 Old 09-13-2011, 06:24 PM
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Quote:
Originally Posted by JPNinPA
P0431 is Bank 2 sensor 2. That is the last three cylinders before the firewall and the O2 below the cat.
1) If you pull the O2 and it looks flattened on one side your cat is on it's way out. Being all 4 O2's are switching the same the front three cylinders may be bad as well.
2) You could have a exhaust leak post the first O2.
3) Bad O2 sensor.

Since you reset the CEL it may take 4 days to come back.
My O2 sensors looked normal with no flattening and the cat was GONE. Not saying you're mistaken at all, just sayin'.

Could you clarify what you mean by "Being all 4 O2's are switching the same the front three cylinders may be bad as well."?


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Quote:
Originally Posted by Ron Paul
“Liberty is lost through complacency and a subservient mindset. When we accept or even welcome automobile checkpoints, random searches, mandatory identification cards, and paramilitary police in our streets, we have lost a vital part of our American heritage. America was born of protest, revolution, and mistrust of government. Subservient societies neither maintain nor deserve freedom for long.”
― Ron Paul
"Did you exchange your walk-on part in the war for a lead role in a cage?"
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