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Trouble Code P0420

This is a discussion on Trouble Code P0420 within the GTO forums, part of the Vehicle Specific category; im having this fault on my car, Code P0420, its says the Catalyt Bank one Efficiency below Threshold. .????...ummm....im thinking ...

  1. #1
    Member pmolina0436's Avatar
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    Question Trouble Code P0420

    im having this fault on my car, Code P0420, its says the Catalyt Bank one Efficiency below Threshold..????...ummm....im thinking because the LT Headers, but if anyone can give me some info on this issue...Or how to disable the Code??? I do have a Diablo Pred..Thanks for help!!!
    Last edited by pmolina0436; 09-09-2008 at 05:48 PM.

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    Grand Imperial Wizard Sarge's Avatar
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    I would delete the rears altogether.

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    Veteran 0rion's Avatar
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    do you have hi-flow cats? I would imagine you're right and it's due to the headers. I'd do like the old man says and just delete the rear codes. How old is your diablo? The older diablo's would let you delete those codes but the newer ones won't. Look under the diagnostic menu and see if there's an option to disable those codes.

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    Member pmolina0436's Avatar
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    P0420

    Quote Originally Posted by 0rion View Post
    do you have hi-flow cats? I would imagine you're right and it's due to the headers. I'd do like the old man says and just delete the rear codes. How old is your diablo? The older diablo's would let you delete those codes but the newer ones won't. Look under the diagnostic menu and see if there's an option to disable those codes.
    Well I tried to disable, but i think i have the newer version so it wont give me he option to DISABLE!!It only gave me the option to RESET!!And im actually going to CAT-LEss on my car!!Is there another way to DISABLE???

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    Veteran 0rion's Avatar
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    not unless you use tuning software or buy O2 sims.

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    Quote Originally Posted by 0rion View Post
    not unless you use tuning software or buy O2 sims.
    Tunning Software????

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    Quote Originally Posted by pmolina0436 View Post
    Tunning Software????
    HP Tuners

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    Member pmolina0436's Avatar
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    P0420

    Quote Originally Posted by FantaZGuy28 View Post
    HP Tuners
    Any other way..I only have Diablo Tunner!!

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    Quote Originally Posted by 0rion View Post
    not unless you use tuning software or buy O2 sims.
    What are 02 Sims???where can i get some??

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    I have had my Diablo Tunner since march and it lets me erase codes. I thought it was because of me cutting my cats out that it was giving me that code P0420, but my diablo tunner has the o2s turned off.

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    Quote Originally Posted by Doug_J View Post
    I have had my Diablo Tunner since march and it lets me erase codes. I thought it was because of me cutting my cats out that it was giving me that code P0420, but my diablo tunner has the o2s turned off.
    I'm a little confused by what you're saying here. Are you saying your diablo let you turn 420 and 430 off or are you saying you're getting that code after cat removal ( which you will) even though the codes are supposed to be turned off.

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    Quote Originally Posted by 0rion View Post
    I'm a little confused by what you're saying here. Are you saying your diablo let you turn 420 and 430 off or are you saying you're getting that code after cat removal ( which you will) even though the codes are supposed to be turned off.
    by disabling the 02 sensors, will that fix the p0420 code

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    Quote Originally Posted by pmolina0436 View Post
    by disabling the 02 sensors, will that fix the p0420 code
    yes, if you just removed the cats disabling those codes will keep the light off. What's not determined is when diable stopped allowing you to do it with their programmer. He says he got his in march but by his statement I can't figure out if he's saying his will turn those codes off or if he tried and is still getting those codes. Also, there are other codes associated with those rear sensors that need turned off if you get rid of the sensors themselves. Heater,activity, and voltage codes.

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    Member pmolina0436's Avatar
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    Quote Originally Posted by 0rion View Post
    yes, if you just removed the cats disabling those codes will keep the light off. What's not determined is when diable stopped allowing you to do it with their programmer. He says he got his in march but by his statement I can't figure out if he's saying his will turn those codes off or if he tried and is still getting those codes. Also, there are other codes associated with those rear sensors that need turned off if you get rid of the sensors themselves. Heater,activity, and voltage codes.
    ok checked out my Diablo and when i go to the 02 sensor option (OBD II 02 sensor) it has various codes such as , P0137,P0138,P0141, P0157,P0158 AND P0160, P0161...WHICH SHOULD I DISABLE??? or do i disable them all!!!

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    Veteran 0rion's Avatar
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    all of them, here's the list for the rear sensors plus the 0420 and 0430:

    DTCs for O2:
    P0137
    P0138
    P0140 what about this one? You didn't list it.
    P0141
    P0157
    P0158
    P0160
    P0161

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    Quote Originally Posted by 0rion View Post
    all of them, here's the list for the rear sensors plus the 0420 and 0430:

    DTCs for O2:
    P0137
    P0138
    P0140 what about this one? You didn't list it.
    P0141
    P0157
    P0158
    P0160
    P0161
    yea forgot that one..But yea it shows up to !!!should i disable them all???or what do you suggest!!!

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    Quote Originally Posted by pmolina0436 View Post
    yea forgot that one..But yea it shows up to !!!should i disable them all???or what do you suggest!!!
    yeah, if you've pulled the sensors go ahead and delete all of them.

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    Quote Originally Posted by 0rion View Post
    yeah, if you've pulled the sensors go ahead and delete all of them.
    thanks for the info...Yea i did disable all REAR sensor , and havent got a problem !!!

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    The code for my o2's come on some times but I got them turned off i don't know why it keeps coming back, but my diablo lets me erase them. maybe thats a little better or should I just shut up?

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    Quote Originally Posted by Doug_J View Post
    The code for my o2's come on some times but I got them turned off i don't know why it keeps coming back, but my diablo lets me erase them. maybe thats a little better or should I just shut up?
    On the Diablo, when you choose the diagnostics option it does let you erase the codes, but then they would just come back on later...what you got to do is DISABLE the 02 sensor codes...just go to the TUNE IT option...then at the very end of the list there should be a option that says 02 SENSORS!!What i did is diable all of them like they suggested...havent had a problem since!!


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