P0420 Catalyst efficiency Code

Discussion in 'Challenger SRT8 Engine & Performance Modifications' started by Tom Joyce, Nov 24, 2021.

  1. Tom Joyce

    Tom Joyce Member

    Posts:
    5
    Likes Received:
    5
    Joined:
    Nov 24, 2021
    Location:
    Nampa, Idaho
    New guy here. I have a 2010 that I redid the motor in about 4 years ago. Whipple, reworked heads, stock SRT8 cam, Kooks long tubes with Kooks high flow cats, Corsa cat back. It kept throwing the catalyst efficiency code so I had my tuner turn rear ones off, unfortunately I have to emissions test it, and it failed due to the sensors being turned off. So I turned them back on and bam, light's back on. So I put Kooks "Green Cats" on it, and still the same. Any ideas? I thought $1200 in cats would fix it, (several people told me it would) but of course it didn't. I had the no-foul extensions on the sensors with the old cats and it still did it, gonna try them on the new ones tomorrow. Any insight on how to correct it would be appreciated!
    Thanks
    Tom
     
  2. Cloverdale

    Cloverdale Full Access Member

    Posts:
    640
    Likes Received:
    185
    Joined:
    May 30, 2020
    Location:
    Cloverdale
    If they're only testing the system for a code or an electronic system alert (and not actual emissions) than maybe you have a time window in which you won't be detectable (when she's cold or for a period of time after you've deleted code)? Mine with similar mods can go for hours w/out throwing a code but eventually does. Otherwise it seems you're at the mercy of the shop / operator doing the testing (perhaps a performance shop will be more willing to work with you / more cooperative than others)? Seems there is also a one year repair or hardship waiver in your state which you might qualify for? We no longer have emission testing in BC Canada so I can't be more helpful.
     
  3. 70-426_10-SRT

    70-426_10-SRT B&E body lover

    Age:
    64
    Posts:
    1,947
    Likes Received:
    894
    Joined:
    Jun 25, 2018
    Location:
    PDX
    There are many P0420 Fixes on-line, most are SCAMS

    My 2010 popped those codes last year.
    I took it in to the dealer three time under Extended Warrantee.
    They finally changed out all four O2 sensors, then told me it was a Bad Cat.
    (DEALER HELP WAS WORTHLESS and a waste of time)

    Luckily, we don't have testing in our county, so I just live with the light-on and reaguarly check codes.

    Please let us know if you figure out a solution
     
  4. Cloverdale

    Cloverdale Full Access Member

    Posts:
    640
    Likes Received:
    185
    Joined:
    May 30, 2020
    Location:
    Cloverdale
    Yes fortunately codes of this nature don't impact performance on our Challengers, unlike BMW and many others!
     
  5. Tom Joyce

    Tom Joyce Member

    Posts:
    5
    Likes Received:
    5
    Joined:
    Nov 24, 2021
    Location:
    Nampa, Idaho
    Yeah no probe in the tailpipe. Once you clear the code, you have to drive it about 50 miles to reset all the monitors in the ECM, it doesn't turn on the light until the next key cycle, and then it comes on within a 1/2 mile. So I'm going to try to hit my testing station before that happens. We'll see.
     
    Cloverdale and 70-426_10-SRT like this.
  6. Danomt

    Danomt Member

    Posts:
    13
    Likes Received:
    4
    Joined:
    May 2, 2021
    Location:
    Glasgow Mt
     
  7. Danomt

    Danomt Member

    Posts:
    13
    Likes Received:
    4
    Joined:
    May 2, 2021
    Location:
    Glasgow Mt
    In the octane post you posted that you were running 100 LL In all my schooling lead will ruin a cat....Just saying....
     
  8. 70-426_10-SRT

    70-426_10-SRT B&E body lover

    Age:
    64
    Posts:
    1,947
    Likes Received:
    894
    Joined:
    Jun 25, 2018
    Location:
    PDX
    ^^^
    Hence why I live "Out-of-Town" up in the mountains, outside "TESTING" requirements.

    :driver:
     
  9. bobbymac

    bobbymac Full Access Member

    Age:
    79
    Posts:
    81
    Likes Received:
    24
    Joined:
    Sep 6, 2021
    Location:
    west babylon NY 11704
    Right on the 50 miles after deleting the code... As for getting to the inspection station before the check engine light goes on.. I tried it - It failed - they knew the up stream censor was out. Give it a try - Just remember - hope for the best expect the worse... bbmac
     
  10. Tom Joyce

    Tom Joyce Member

    Posts:
    5
    Likes Received:
    5
    Joined:
    Nov 24, 2021
    Location:
    Nampa, Idaho
    Well, I got it to reset all the emissions monitors long enough to pass. Still need to fix it so the light isn't on all the time, but I'll take it for now. Thanks for all the replies
     
    Cloverdale likes this.