Thread: P420 code

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  1. #1 P420 code 
    GrandPrix Junkie Bluemagic's Avatar
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    Well I'm finally getting the cat changed tomoro. Noticed while driving on slow acceleration rpms drop at like 50mph or so then just drags. Just want be sure it's the cat and not the sensor. Well I changed the sensor and the damn light came back so... I'm guessing it's the cat lol. Any thoughts about the rpms dying at 50 miles per hour? Sound like a typical cat issue?
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  2. #2 Re: P420 code 
    Turbo is the way to go. BillBoost37's Avatar
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    Looks, smells and sounds
    I drink..so consider that when reading my posts.

    2010 Audi A6 Dual IC's
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  3. #3 Re: P420 code 
    GTP Level Member Rico's Avatar
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    The downstream sensor just monitors catalytic convertor efficiency...I don't think it has anything to do with the way the motor runs.
    Get the convertor replaced before you do anything else. This is hell on the engine.
    It's a CUMMINS Dodge not a Dodge Cummins
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  4. #4  
    GrandPrix Junkie Bluemagic's Avatar
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    Sounds awful. Took it in to check for leaks and they found none. So cat goes bye bye gotta get a confirmed price though. The exhaust shop charged my friend 160 then tried to charge me 225 for the same Job. Wtf.
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  5. #5 Re: P420 code 
    GTP Level Member Rico's Avatar
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    Quote Originally Posted by Bluemagic View Post
    Sounds awful. Took it in to check for leaks and they found none. So cat goes bye bye gotta get a confirmed price though. The exhaust shop charged my friend 160 then tried to charge me 225 for the same Job. Wtf.
    They may have welded his in...and you may be getting an entire downpipe?
    It's a CUMMINS Dodge not a Dodge Cummins
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  6. #6  
    GrandPrix Junkie Bluemagic's Avatar
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    Naw I have a downpipe and yea they weld everything. They are known to fluctuate in prices when different people are there but when i show them my club logo they give me a discount. Smh.
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  7. #7  
    GrandPrix Junkie Bluemagic's Avatar
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    Cat done car feels a lot more responsive and doesn't drag at all anymore. Now let's hunt down this misfire from cylinders 1 and 4 lol
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  8. #8 Re: P420 code 
    Turbo is the way to go. BillBoost37's Avatar
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    Check again...Likely they were from the cat.
    I drink..so consider that when reading my posts.

    2010 Audi A6 Dual IC's
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  9. #9  
    GrandPrix Junkie Bluemagic's Avatar
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    I wish. This happened after the cat lol
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  10. #10 Re: P420 code 
    Turbo is the way to go. BillBoost37's Avatar
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    1/4 you say.. odd how they are both on the same coil. Bet if you swapped that with the 2/5 right above it..that 2/5 would probably start messing up, leading you to replacing that coil
    I drink..so consider that when reading my posts.

    2010 Audi A6 Dual IC's
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  11. #11  
    GrandPrix Junkie Bluemagic's Avatar
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    Ok I'll try that, my car started throwing a p300 code. Which said multiple misfire. So I fired up my torque app and brought up each cylinder and found out that the 1st and 4th cylinder was the culprits. Is removing and switching the coils easy?
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  12. #12 Re: P420 code 
    Turbo is the way to go. BillBoost37's Avatar
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    Each of our three coils fires two cylinders. it fires both posts at the same time, which is why our system is called a waste spark system. It fires the coil to ignite 1, and throws away a spark during the exhaust of 4.

    Swap the 1/4 and 2/5 coils and likely the misfires will move to the 2/5 cylinders instead of 1/4. If that happens, replace the bad coil.
    I drink..so consider that when reading my posts.

    2010 Audi A6 Dual IC's
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  13. #13  
    GrandPrix Junkie Bluemagic's Avatar
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    Ok thanks. Great info by the way. Learn something every day
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  14. #14 Re: P420 code 
    Turbo is the way to go. BillBoost37's Avatar
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    Your next tip is ... 14 beers is what it takes to start working on a 1988 Ford van motor swap. 4 advil the next morning help with the repercussions
    I drink..so consider that when reading my posts.

    2010 Audi A6 Dual IC's
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  15. #15  
    GrandPrix Junkie Bluemagic's Avatar
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    Lol. I will take note of that. Thanks so much for your help. Love these forums!
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  16. #16 Re: P420 code 
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    GM should have had a recall on these cats..everyone says they should last the life of the vehicle
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