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Northstar Engines and System Technical Discussion Discussion, P0420 Code in Cadillac Engine Technical Discussion; hopefully this link will work. ....
  1. #76
    koolfred2002 is offline Cadillac Owners Member
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    Re: P0420 Code

    hopefully this link will work. .

  2. #77
    koolfred2002 is offline Cadillac Owners Member
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    Re: P0420 Code

    U didn't think a caddy would sound like that did ya. I would not mind having that exaust but over $1000 freakin dollars and I think it my be to loud! but I would Love to have those exaust tips.

  3. #78
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: P0420 Code

    You don't have exhaust tips like that? You could probably find a set on Ebay.

  4. #79
    Submariner409's Avatar
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    Re: P0420 Code

    Quote Originally Posted by koolfred2002 View Post
    U didn't think a caddy would sound like that did ya. I would not mind having that exaust but over $1000 freakin dollars and I think it my be to loud! but I would Love to have those exaust tips.
    Take it from someone who has had the CORSA system on his STS since 11/06: It's NOT loud unless you want it to be - absolutely silent at cruise but stick your foot in it and it will wake the dead. The problem with these factory exhaust systems is not the cat or mufflers - it's the small pipe from the cat to the Y, the Y itself, and the pipes to each muffler. CORSA addresses all that and more. If you want the real thing, be ready to pay for it. Mufflers alone may sound good but they don't do squat for performance (more noise is more power, right ?).

    CORSA sells tips, mufflers, parts at www.corsaperformance.com

    Systems for 1999 and + at www.AutoPartsWarehouse.com

  5. #80
    screech858's Avatar
    screech858 is offline Cadillac Owners Member
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    Re: P0420 Code

    Quote Originally Posted by derone View Post
    Hey, been there, done that. I even bought one of those 'direct-fit' cats and can tell you direct-fit don't mean sh$t. Then I found that all cats aren't the same as some would lead you to believe. I had the 420 error and I have been using the Magnaflow 46006 cat for over 40k miles with no codes. It has the 2.5" in and out connections....the 46009 has 3". Double check to see which pipe yours has, as their application chart isn't that accurate. See link for more info: http://www.car-sound.com/02product/u...alCARB/460.asp
    Did you notice and difference in sound when swapping out the factory cat and installing the magnaflow one?

  6. #81
    Submariner409's Avatar
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    Re: P0420 Code

    derone hasn't been here for over a year. With a stock exhaust system there will be little, if any, sound change when replacing a converter. The original converter is a honeycomb ceramic high-flow unit - it's the resonator that smooths out the front exhaust pipe sound pulses.

  7. #82
    screech858's Avatar
    screech858 is offline Cadillac Owners Member
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    Re: P0420 Code

    cool thanks man

  8. #83
    NHRATA01 is offline Cadillac Owners Fanatic
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    Re: P0420 Code

    Quote Originally Posted by submariner409 View Post
    derone hasn't been here for over a year. With a stock exhaust system there will be little, if any, sound change when replacing a converter. The original converter is a honeycomb ceramic high-flow unit - it's the resonator that smooths out the front exhaust pipe sound pulses.
    I might have to disagree with ya on that one sub. In my experience the factory-style honeycomb ceramic units tend to absorb much more of the exhaust volume then a straight-through metal matrix design of a typical aftermarket cat.

    For many years I had essentially a straight-pipe exhaust with a resonator on my LS1 Trans Am (SLP loudmouth). It sounded nice with the factory converters. It was still liveable with an old header manufacturer that utilized honeycomb ceramic cats on the headers. When I switched to a set of American Racing headers with the metallic style cats, basically the magnaflow ones, it became unbearable. And I tend to have a pretty large tolerance to exhaust noise!

  9. #84
    MoistCabbage's Avatar
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    Straight pipe with resonators, no mufflers---not a stock exhaust system.

    Swapping cats may make some slight difference, but nothing too noticeable (with mufflers).

  10. #85
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    dtaylor is offline Cadillac Owners Member
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    Re: P0420 Code

    I also have the p0420 code. I'm gonna look into the magnaflow 46006 I hope this will take care of this code Dont care about sound I just want this engine light GONE

  11. #86
    oldmanlesabre is offline Cadillac Owners Fanatic
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    Re: P0420 Code

    so apparently the 'new' magnaflow seems to work, but the model before the one out now is complete garbage? so many mixed reviews. what is difference with 46006 and 46009? just got done reading this thread:
    http://www.cadillacforums.com/forums...y-p0420-4.html

    and others...

  12. #87
    mustangrr is offline Cadillac Owners Member
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    Re: P0420 Code

    PO420 has got me too...
    My 2003 SLS with 77K miles just popped the SES and analysis showed a PO420 code. Local mechanic told me the catalytic convertor was bad. I had him replace it to the tune of $550. About a week later I started noticing my engine was running oddly (the SES light had gone off a couple of days earlier, after having had the CAT replaced) - rough and weak at stops, but powerful when accelerating, almost like it had a modified cam in it suddenly. I started thinking about timing, and rich & lean fuel mixtures - but once under the hood I discovered a loud sucking noise, and realized I had a vacuum leak. I took the car to my local Chevy/Cadi dealership, where they analyzed the problem and came up with a cracked Throttle Body Boot. After 3.5 hours of labor, a new Throttle Body Boot, $400 and a reset computer registry, I was on my way. Suddenly, two weeks later, my SES has come on again. Took the car to a local Autozone and had them do the computer analysis and the code came up PO420 again!!??

    Having read all the previous posts in this thread, I'm wondering if the replaced CAT was an inferior after-market, and perhaps has failed, or not able to meet the standards anymore - or, could the sudden cracking of the Throttle Body Boot (TBB) and the resulting vacuum leak cause the CAT to fail? Is this logical thinking on my part? I ask because I'm not sure where to start looking for a remedy. My first thought is to find out if the replacement CAT was worthy of Cadillac usage. Any other thoughts, suggestions and/or remedies will be appreciated.

    PS. Because the SES light went off between the CAT replacement and the onset of the vacuum leak due to the cracked TBB, I assuming this new PO420 code is a current reading and not a history reading, though I'm not positive right now. I have been driving the car with the SES light on for about 4 days now without any notice of problems.

  13. #88
    Submariner409's Avatar
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    Re: P0420 Code

    GM refers to your "throttlebody boot" as a "plenum". P/N 12555840, about $30.

    Your car has its own built-in code memory/reader/scanner system right in the DIC. Study the sticky post ^^^ "How to pull codes". You want the proper procedure for the cars with 3 DIC control buttons on the right and OBD-II (obd2) protocol. Practice, write down all codes and whether each is Current or History, then return to the sticky to open the link with "obd2" in the address to get to a Master Index of all P,B,C, and U code definitions. Always post definitions along with codes.

  14. #89
    mustangrr is offline Cadillac Owners Member
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    Re: P0420 Code

    Thank you Submariner409 - Sounds like a mouthful of terminology I have to research and catch up on. I assume my logic about researching the replacement CAT is okay, once I determine whether I'm looking at historical or current coding, right?

  15. #90
    mustangrr is offline Cadillac Owners Member
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    Re: P0420 Code

    And you're right on the Plenum cost - the dealer charged me $36.60 for it, and $330 for labor...

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