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PO420 code

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Old 01-27-2011, 02:18 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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Old 01-27-2011, 02:31 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, 02:33 PM
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Along with the plenum and cat.
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Old 01-27-2011, 02:37 PM
Jamie71 Jamie71 is offline
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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, 03:35 PM
pcfixerpro pcfixerpro is offline
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Quote:
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, 04:07 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, 04:30 PM
Jamie71 Jamie71 is offline
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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, 04:34 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, 05:53 PM
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A 420 code is the one before the cat.......
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Old 01-27-2011, 05:59 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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