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Guest Message by DevFuse

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Oxygen sensors and P0420 codes

legacy subaru oxygen sensor P0420

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1 reply to this topic

#1 luko


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Posted 26 September 2013 - 04:43 PM

Okay so here is my question, I have a 2001 Lego 5 speed with 125,xxx miles on her, and  Is there any difference between O2 sensors for the automatic and manual? 

       On Subaru Parts For You it lists that there are two different O2 sensors as seen here:  http://subarupartsfo...xygen&year=2001  


     I just wanted to know of this was true or not because my car has the dreaded P0420 code and I have done everything to get if off such as running NGK spark plugs, OEM Beck Arnely wires, OEM coil pack when the original one went bad, new air filter, fuel filter, intake gaskets, head gaskets, and I already did a timing belt kit on it when it hit that interval including thermostat (used the proper one, not the ordinary one) water pump, and I'm running good 89 octane gas threw her. 

     So the only thing left is to change the front O2 sensor and I have a used one that was good out of a 2000 outback but it was an automatic so I'm not sure if they would interchange. 


    I'm going to try the seafoam trick tomorrow to see what that does. My New York state inspection is up in a couple of months and it needs to pass the OBII check being 1996 and newer...good ol' NYS!!!  

#2 idosubaru


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Posted 26 September 2013 - 06:01 PM

auto/manual shouldn't matter.  subaru has a site called opposed forces - google it and it cross references all parts like that for you.


that being said - do you have any exhaust leaks?  you can't have any exhaust leaks.


cardoc has an extensive thread on subaruoutback.org - it details how you need to read the ECU data to determine what's wrong - could be a litany of things causing improper fueling.  find that thread and he details a few causes he has found - read that thread before you do anything else - or at least the first page.


if you don't do that the only way you'll "fix" it is to install a new converter $$$$$$ - which will in turn fail in the future for the same reason the original failed.


keep in mind - all Subaru converters last the life of the vehicle and should never need replaced, if they do then something "caused" it and needs remedied before you install a new expensive converter...unless you like throwing expensive parts at issues.


the problem is analying that data is something no mechanic does (except cardoc in Austin, Texas at his shop), folks on subaruoutback are getting free software to read the data and posting it for him to look at the fuel trims and ascertain what's wrong.  quite a few threads have been started over there.

Also tagged with one or more of these keywords: legacy, subaru, oxygen, sensor, P0420

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