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OBDII scan code P0420 - Need Freeze Files read - Please!

Discussion in 'Technical Chat' started by gdyer911, Nov 3, 2007.

  1. Nov 3, 2007 at 6:02 PM
    #1
    gdyer911

    gdyer911 [OP] New Member

    Joined:
    Nov 3, 2007
    Member:
    #3351
    Messages:
    4
    Vehicle:
    99 Tacoma 4X4 Xtra cab
    I am attaching the following freeze frame files and a capture of the data for a P0420 scan code - They are from a 99 Tacoma 2.7 70k with all the exhaust leaks just repaired, new CAT, and MAF throughly cleaned.

    I purchased the truck about 3 months ago, with a small exhaust leak...the CEL came on after having it about 3 weeks. So I had the CAT replaced after the shop told me it had a P0420 code...ran for a week and the CEL came back on...had them repair a leak at the manifold, and a gasket leak at the manifold/CAT joint. All is quiet now...and the engine seems to purr...BUT the CEL came back on ...so I figured I'd have a look myself (invested in a ELM327 scanner)...
    I read in the Haynes manual the #1 sensor should be between .1 & .9 and the second sensor approx half the first.

    The problem is-- with a warm engine at idle...the readings fluctuate/bounce as you can see in the readouts..

    Is this typical of bad...sensor 1/2? Bad MAF...too rich mixture..or what...

    I picked up a ELM327 scanner and am having a really hard time understanding the results of the captured data.


    Thanks in advance for taking a look at the files..and your technical help...any guidance will help...THX!

    Greg

    Scanshot1.jpg
    Scanshot2.jpg
    Scanshot3.jpg
    Scanshot4.jpg
     

    Attached Files:

  2. Nov 3, 2007 at 8:26 PM
    #2
    Spyder327

    Spyder327 Well-Known Member

    Joined:
    May 25, 2007
    Member:
    #1677
    Messages:
    204
    Phoenix, AZ
    Vehicle:
    2005 X-Runner
    Aquamist 2D meth/water injection kit, URD Exhaust, DT Long Tube Headers, Hood Struts, and lots of other miscellaneous stuff...
    Do you know what kind of new CAT is on there now? P0420 is typically a CAT not working properly. If it's an aftermarket one thats considered "hi-flow" at all, it may still signal the light just like if the OEM ones were blown or not there.
     
  3. Nov 4, 2007 at 5:10 AM
    #3
    gdyer911

    gdyer911 [OP] New Member

    Joined:
    Nov 3, 2007
    Member:
    #3351
    Messages:
    4
    Vehicle:
    99 Tacoma 4X4 Xtra cab
    It's a generic replacement...I tried to make it a cost effective replacement...dang...
     
  4. Nov 4, 2007 at 6:45 PM
    #4
    AUDITECH

    AUDITECH Carolina Alliance: LAZY DIVISION

    Joined:
    Feb 10, 2007
    Member:
    #875
    Messages:
    840
    charlotte nc
    Vehicle:
    07 double cab prerunner
    none
    the snesors should be jumping from high to low or lean to rich for proper cat function. Now that you got a new cat and no exhaust leaks your o2 sensors could be junk.
     
  5. Nov 4, 2007 at 6:56 PM
    #5
    gdyer911

    gdyer911 [OP] New Member

    Joined:
    Nov 3, 2007
    Member:
    #3351
    Messages:
    4
    Vehicle:
    99 Tacoma 4X4 Xtra cab
    Sorry...can you elaborate on the "junk"? Meaning that with the new CAT the sensors are junk as in needing replacement...or useless..or...??

    Thanks for the the clarification in advance!
     
  6. Nov 8, 2007 at 2:33 AM
    #6
    AUDITECH

    AUDITECH Carolina Alliance: LAZY DIVISION

    Joined:
    Feb 10, 2007
    Member:
    #875
    Messages:
    840
    charlotte nc
    Vehicle:
    07 double cab prerunner
    none
    yes the old o2 could be bad with the previous exhaust leak. sorry for the misscomunication
     
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