where to go for my P0420 code

Discussion in 'General Subaru Discussion' started by esperunit, Feb 14, 2005.

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  1. esperunit
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    esperunit Well-Known Member

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    I got a P0420 CEL the other day. Seems pretty straight forward, the cat is out and it needs a new one. Which twin cities dealership is going to gie me the least amount of warranty hassle for this considering I have an intake and Catback?
     
  2. Zola
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    Zola Well-Known Member

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  3. Zola
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    Zola Well-Known Member

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    Whoops, I suppose I should read more carefully before I reply. You want to have the cat section replaced under warranty?

    With an intake and a catback, even though the likelihood of either of them causing the failure of your catalyst is likely nil, I wouldn't count on getting much love from a dealership.

    Anyway, you can either wire up that gizmo I posted above or search NASIOC for the "mechanical fix", which involves spending a few bucks on some hardware and a little drilling. Either of these will prevent the P0420 trouble code.
     
  4. esperunit
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    esperunit Well-Known Member

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    yeah saw that nasioc fix. I was hoping to get a new factory cat first, then when that one breaks, ride it out solo.

    Oh well, looks like a fight with the dealership. Hopefully they won't put up too much of a battle.
     
  5. AWDimprezaL
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    AWDimprezaL has more posts than you

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    p0420 is a fuel trim code, i dont think it has anything to do with cats...i got this when a hose on my intake was cracked, do you have an aftermarket intake? subaru computers run on a learning curve and that curve can only go so far, thats when the CEL comes on...look at your vaccume lines and so forth, my work, morries MTK subaru would warranty it, probably no questions asked, but i dont think that is your problem
     
  6. esperunit
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    esperunit Well-Known Member

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    well, according to nasioc, all of the p0420 codes there have to do with catalytic conversters, or sometimes, but rarely 02 sensors.

    Not to mention I have no hoses on my intake. It's an 02, so the intake is different than the GC8's

    But if you work at morries, can you let me know if there is a time on tues or weds i could bring it by for someone to take a look at a clunk i'm getting on my left side of my suspension/engine compartment?

    It would really help me out a lot.
     
  7. AWDimprezaL
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    AWDimprezaL has more posts than you

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    well, i dont work as a mechanic, but two brothers on this forum that have yet to show themselves do, ben or brian help this guy out!
     
  8. esperunit
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    esperunit Well-Known Member

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    actually I knocked out the clunk this evening with a tightening of the strut top bolt. I had no idea it could be the problem and I feel dumb after checking, well literally everything else. I was even considering wheel bearings, even though I knew that a lot of the symptoms didn't exactly match up.

    I still need to get this CEL thing sorted out, looks like I'll probably head to Morries to do that, if they won't put up a fight against my catback and intake
     
  9. Zola
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    Zola Well-Known Member

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    <blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Originally posted by AWDimprezaL

    p0420 is a fuel trim code, i dont think it has anything to do with cats...
    <hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

    That's not correct. P0420 is the rear catalyst inefficiency code. It has no performance impact at all, since the ECU does not use any information from the rear O2 sensor for fueling changes.
     
  10. AWDimprezaL
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    the scan tool i used said p0420 was fuel trim
     
  11. driftin240
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    driftin240 Well-Known Member

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    Hey Dudes, This Is Brian...The Suby Mechanic. Normally the P0420 comes on when the cats are running low efficiency, In other words need to be replaced. Here's The deal, bring the car in to minnetonka suby and request that brian on the blue team takes care of it and we'll get ya goin again...CEL free!
     
  12. esperunit
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    esperunit Well-Known Member

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    well, looks like that won't be neccesary. I figured out the problem and it won't need a new cat. It was overfilled gas. A friend filled it up while I was at the gas station, and I forgot that the CEL came on as I was leaving the station, which was a dead giveaway. After the tank was gone, the CEL went off on the next tank.

    But I'm sure I haven't seen the last of it, so I'll probably be taking it in one of these days.
     
  13. DISCOPOPE
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    DISCOPOPE Well-Known Member

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    fwiw, i have a code puller/clearer now if anyone needs help.

    just give me a hollar.
    612.379.2321
    aaron
     
  14. AWD 101
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    AWD 101 Well-Known Member

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    can anyone elaborate on why overfilled gas would cause a cat-efficiency CEL? good to know for future reference that this can happen on a wrx.
     
  15. DISCOPOPE
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    DISCOPOPE Well-Known Member

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    no clue at all.
     
  16. esperunit
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    esperunit Well-Known Member

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    i happened all the time on my old land cruiser.

    I'm not aware of why it happens, but this is what they always told me when it happend on the land cruiser. And it made sense, since it was tripping tha cat CEL on that car too, and that had no modifications whatsoever.

    But i'd like to know why overfilling gas messes up the catalytic converter too.

    EDIT: here is a good explanation, taken from emissioncheck.com

    2) Do not overfill the gas tank. When you fill your tank, resist the impulse to get just a "little bit more" into the tank after the nozzle clicks off. The excess gasoline has nowhere to expand and may saturate a part of the emissions system.
     
  17. Grimm
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    Grimm New Member

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    <blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Originally posted by DISCOPOPE

    no clue at all.
    <hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
    bump
     
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