Thread: P code P0431

  1. #1
    navygm1's Avatar
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    P code P0431

    Warm up catalyst efficiency Bank 2 below threshold.
    Already replaced both O2 sensors on bank 2. Took a look at the cat with an endoscope and did not see a blockage.
    What else could the issue be?


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    Re: P code P0431

    Also it is a 2006 wrangler.


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    P code P0431

    Did you use NTK O2 sensors?

    P0431 is Bank 2 sensor 2. That is the last three cylinders before the firewall and the O2 below the cat.
    1) If you pull the O2 and it looks flattened on one side your cat is on it's way out. 2) You could have a exhaust leak on that header. Last bolt is known to back out over time. 3) Bad O2 sensor.
    Try to reset the CEL to see if it comes back. it may take 4 days to come back.

    No blockage was there anything in the cat? Mine was empty.

    Easy way to check exhaust leak.
    Hook your shop vac hose to the vac output to use as a blower. Then connect the other side of the hose to the exhaust tail pipe. You might duct tape nit on. When engine is off and cold. Turn the vac on blowing up the pipe. Feel around the connections for leaks.
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    Last edited by JPNinPA; 07-13-2019 at 06:08 PM.
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    Re: P code P0431

    O2 is new.
    I will check the other stuff


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    Re: P code P0431

    The 2nd cat was missing a bolt, so was lose. Replaced bolt, still got P0431. Took O2 sensors out and used an endoscope to look through the upper O2 connection, saw only the honey comb.


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    P code P0431

    Is the new O2 NTK brand?
    Try the vac exhaust trick to be sure there are no leaks. It doesn’t take much.

    Did you clear the codes?


    Reset PCM

    1.) Disconnect the POSITIVE battery Terminal and touch it to ground for 30 seconds to discharge the PCM capacitors, which maintain the Adaptive Memory.
    2.) Reconnect the Battery Cable.
    Turn Ignition Switch to the “On” position but DO NOT start the engine.
    3.) Turn Headlight On.
    4.) Turn Headlights Off.


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    Last edited by JPNinPA; 07-13-2019 at 07:02 PM.
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    Re: P code P0431

    Quote Originally Posted by JPNinPA View Post
    Is the new O2 NTK brand?

    •Try the vac exhaust trick to be sure there are no leaks. It doesn’t take much.

    I used the shop vac to blow through the exhaust. Cat 1 was leaking, tightened that up. Took the O2 sensor out of cat bank 2/1 while the vac was blowing got a great flow of air. While I had the O2 sensor out I switched nozzle to suction and got great suction through the hole. Put everything back together.


    Reset PCM

    1.) Disconnect the POSITIVE battery Terminal and touch it to ground for 30 seconds to discharge the PCM capacitors, which maintain the Adaptive Memory.

    •Took the positive side off and the connector fell apart in my hand. Grounded it out.

    2.) Reconnect the Battery Cable.
    Turn Ignition Switch to the “On” position but DO NOT start the engine.

    • did.

    3.) Turn Headlight On.
    4.) Turn Headlights Off.
    • did

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    Now I just got to drive for a bit to see what happens.



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    Re: P code P0431

    Got my fingers crossed.


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    JPNinPA

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    Cool Re: P code P0431

    I think i found out what the problem might be! SB 25-005-13
    Attached Thumbnails Attached Thumbnails P code P0431-sb-25-005-13.pdf  


  10. #10
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    P code P0431

    I take it you still have the code. Thanks for sharing that TSB. Never saw that before.

    Best part is the last line

    NOTE: Vehicles included in this Service Bulletin have a lifetime coverage warranty for this repair. See Warranty Bulletins; U.S. D-13-38, Canada SAB-2013-29 or International ID-13-12 for details associated with the extended warranty


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