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PO420 code

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  #1  
Old 01-27-2011, 01:18 PM
Jamie71 Jamie71 is offline
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Default PO420 code

Hey, i have a PO420 code, i know what it is but I dont know where it is located on the exhaust. Catalyst System Efficiency Below Threshold (Bank 1). Any help would be great to where it is located.
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  #2  
Old 01-27-2011, 01:31 PM
dodgeboy1979 dodgeboy1979 is offline
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i believe that is the precat o2 sensor. Probably time to change both of them out if they are old
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Old 01-27-2011, 01:33 PM
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Along with the plenum and cat.
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Old 01-27-2011, 01:37 PM
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So the o2 sensor before the cat converter? I think there are 2 of them right?
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Old 01-27-2011, 02:35 PM
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Originally Posted by Jamie71 View Post
So the o2 sensor before the cat converter? I think there are 2 of them right?
No, dodgeboy1979 is incorrect. It is the post-cat sensor. And to answer your question, yes there are two sensors in a non cali emissions truck.
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Old 01-27-2011, 03:07 PM
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Jamie, is your cat hollowed out by any chance? My cat is gutted and I occasionally get the P0420 code because of it. If I don't clear it myself it usually goes away after a while. If your cat isn't gutted, it may be getting plugged. 90% of the time it's the cat at fault, not the O2 sensor.
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Old 01-27-2011, 03:30 PM
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My code doesnt go away unless i clear it and I am trying to figure out where behind the cat converter is the bad o2 sensor since it is the Catalyst System Efficiency Below Threshold (Bank 1).
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Old 01-27-2011, 03:34 PM
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Should be shortly behind the cat. If it isn't there.... that would explain a lot. Shouldn't be more than foot or so away. Might be on top of the pipe.
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Old 01-27-2011, 04:53 PM
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A 420 code is the one before the cat.......
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Old 01-27-2011, 04:59 PM
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P0420 1/1 Catalytic Conv Eff

Wonder if it is referring the cat, or the sensor..... not what I would really expect to see for a failing O2 sensor.... but then, it IS a dodge.....
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Old 01-27-2011, 05:04 PM
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Quote:
Originally Posted by zman17 View Post
A 420 code is the one before the cat.......
+1 Y'up...0423 is after the cat
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Old 01-27-2011, 07:53 PM
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Originally Posted by Jamie71 View Post
Catalyst System Efficiency Below Threshold (Bank 1).
How does the pre cat sensor read catalyst efficiency if its sensing exhaust BEFORE the cat. Just my .02, but the post cat sensor makes more sense with the way the code is worded
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Old 01-27-2011, 10:06 PM
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How does the pre cat sensor read catalyst efficiency if its sensing exhaust BEFORE the cat.
Exactly, Someone gets the big picture

http://www.p0420.com/ <-- Reading material for the ****ter

Rear o2 is what is throwing the code, but not necessarly the reason for the code.
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Old 01-27-2011, 11:40 PM
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Jesus Christ, p0420 is not an o2 sensor code. Its for catalytic converter efficiency. Basically your cat is dead. Meaning its no long cleaning the emissions from your engine. Don't replace your 02 sensor your wasting your money. You should replace (or hollow out) your cat. BTW If you hollow it out your going to get a cel.
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Old 01-27-2011, 11:47 PM
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Originally Posted by Dodgeman000 View Post
Jesus Christ, p0420 is not an o2 sensor code. Its for catalytic converter efficiency. Basically your cat is dead. Meaning its no long cleaning the emissions from your engine. Don't replace your 02 sensor your wasting your money. You should replace (or hollow out) your cat. BTW If you hollow it out your going to get a cel.

Po420 IS an o2 sensor code. The catalyst efficiency is read by the post cat o2 sensor. It is possible that the o2 is lying to the pcm because it is faulty. Therefore the root of the problem could be that the o2 is bad or the cat is sh!tting the bed.

Only reason I asserted my opinion on the meaning of the code is to shoot down the naysayers with some good ol' logic. My money is on the cat being clogged by a blown plenum, but we cant rule the o2 out of the equation.

Edit: If you gut your cat there is a quick and painless way to eliminate the CEL. Use the spark plug non-fouler trick which can be found in the faqs section here (works for me and many others on this site). It is quick, easy and will set you back a whopping 5$. NOTE: If you must pass smog emissions (i.e. they put a hose on your exhaust) you will not pass with a gutted cat
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Old 01-28-2011, 02:25 AM
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well if your replacing the cat just do your sensors too. might find better fuel efficiency with new sensors and new cat. BTW if you have problem with emissions move to a state without them. ha ha +1 for Minnesota.
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Old 01-28-2011, 02:58 AM
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well if your replacing the cat just do your sensors too. might find better fuel efficiency with new sensors and new cat. BTW if you have problem with emissions move to a state without them. ha ha +1 for Minnesota.

Dont fix what aint broke. If your o2s are good, leave them there.
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Old 01-28-2011, 07:54 AM
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Right out of our own FAQ section, http://dodgeforum.com/forum/1582321-post6.html. 1/1 means bank1/ sensor1. We can argue all day about what catalytic converter efficiency means, but 1/1 is the precat sensor.
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Old 01-28-2011, 09:51 AM
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Everytime i check different sites about the code it sayd it is the o2 sensor not the cat it self, so I am taking it is the sensor just before the cat.
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Old 01-28-2011, 09:54 AM
Jamie71 Jamie71 is offline
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So what is it- the cat or the o2 sensor? I think it is the o2 sensor.
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Old 01-28-2011, 09:54 AM
 
 
 
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