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o2 sensor help. bank 1 sensor 1

Discussion in '1st Gen. Tacomas (1995-2004)' started by vtwinjunkie, Sep 16, 2017.

  1. Sep 16, 2017 at 2:05 PM
    #1
    vtwinjunkie

    vtwinjunkie [OP] Well-Known Member

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    2.5 inch lift and 33's
    Hey all

    So on the the next issue with the new truck not that I have the airbag light all worked out.

    I am having an issue with a p0420 code and after following the procedure as outlined in the fsm (using an OBD2 scan tool) I am unable to get a signal from the bank 1 sensor 1 (upstream o2 sensor).

    I am not certain if this means that it just has no voltage or perhaps there is an electric issue in the wiring leading to the o2 sensor....

    anyhow,

    Before I go buying a $100+ dollar o2 sensor I was wondering if anyone had an old one lying around (dont care if it is bad) just to test on my truck?

    I would gladly pay shipping or if you are local to the washington DC area Ill come get it!


    any help or insight would be appreciated.

    Thanks
     
  2. Sep 16, 2017 at 2:53 PM
    #2
    License2Ill

    License2Ill Shitiful

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    It's a dry heat thou, AZ
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    Might want to list year and transmission of truck or include the p/n for the sensor...
     
  3. Sep 16, 2017 at 2:54 PM
    #3
    Wyoming09

    Wyoming09 Well-Known Member

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    Ok just what did you do??

    First that code means that the Cat Efficiency has dropped below what is considered in the range

    Does this Have the California Emissions which was the two cats

    it is most often the down stream sensor that fails

    It can also be anything in the complete circuit

    Something as simple as a bad gasket between the cats the O2 sensor vibrating loose .

    The wires falling on the exhaust is also common

    Wires rubbing through
     
  4. Sep 16, 2017 at 4:20 PM
    #4
    Fstrnyou

    Fstrnyou Well-Known Member

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    Many many miles.
    When you do fix it, be sure to clear the code.

    I just replaced mine due to faulty heater circuit. Took it for a spin and was hoping the code would clear itself. Drove the same crappy way it did with the bad sensor. Parked it, disconnected the battery, and let it sit while I did a few chores around the house. Hooked it back up and CEL is off, drives fine for the first time since I bought it.
     
    Dalandser likes this.
  5. Sep 16, 2017 at 4:35 PM
    #5
    toyrunner

    toyrunner Puddle Jumper

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    Kings in front, Bilstien Reservoir rears, Custom sway bar disconnects, 265/75 16 BFG AT's, ARB front bumper and FROR rear bumper. Bao-Feng 2 meter radio and Cobra CB
    I don't know what truck year you have or 4-6 cyl. This fits a 6 banger 04 taco with automatic
    https://www.amazon.com/gp/product/B000C5YCRA/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1
     
  6. Sep 16, 2017 at 9:15 PM
    #6
    vtwinjunkie

    vtwinjunkie [OP] Well-Known Member

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    2.5 inch lift and 33's
    Sorry I have a 2002 2.7 4cl manual trans.
     
  7. Sep 17, 2017 at 7:48 PM
    #7
    vtwinjunkie

    vtwinjunkie [OP] Well-Known Member

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    As I stated in my first post. I followed the factory service manual to test the code. I understand that it was a code for a cat efficiency but the toyota service manual has a simple set of steps to diagnose.

    the first step was check for exhaust leaks. the second step was to test the o2 sensors. since I cannot get my obd2 scan tool to get a reading from the front cat, but I can get a signal from the second cat, I figured I would start there first.

    I the electrical connections of both cats are intact and making good connection and the wires look good and not damaged, along with the sensors being properly bolted down. however I am unable to get a signal from the front sensor.
     
  8. Sep 17, 2017 at 8:07 PM
    #8
    Bulldogs129

    Bulldogs129 Don't find fault, find a remedy

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    This is a '02 Tacoma 3.4l...

    Test the upstream & downstream

    Bad upstream...

    IMG_9614.jpg

    Good downstream...
    IMG_9616.jpg

    FYI...I replaced my catalytic converter and upstream
    IMG_9577.PNG.jpg


    Good luck!
     
    Last edited: Sep 17, 2017
    Dalandser likes this.
  9. Sep 17, 2017 at 8:29 PM
    #9
    127.0.0.1

    127.0.0.1 AKA ::1

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    read the toyota docs on how to correctly test bank 1 sensor 1. sensor 1 is always an air fuel sensor

    it is not an o2 sensor. the proper name of if it air/fuel sensor, sometimes called
    wideband o2...and it is not able to be tested the same way as an o2. it operates
    differently and has different electrical characteristics and the docs at techinfo.toyota.com
    tell you how to test one. a bit different than simple resistance you can do with an o2 sensor

    if I recall correctly
    air/fuel is not able to be tested through obdII other than pass/fail or throw
    it's own code, such as heater circuit malfunction...it can be tested via techstream and the techstream interface
     
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  10. Sep 17, 2017 at 9:04 PM
    #10
    vtwinjunkie

    vtwinjunkie [OP] Well-Known Member

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    Wonderful response!

    Did you also have the p0420 code?
     
    Bulldogs129 likes this.
  11. Sep 17, 2017 at 9:08 PM
    #11
    Bulldogs129

    Bulldogs129 Don't find fault, find a remedy

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    Yep. There's some good troubleshooting tips for this code on YouTube. Take your time, and you'll find the issue. The cat can function at 94% and still cause a code.
     
    Last edited: Sep 17, 2017
  12. Sep 17, 2017 at 9:12 PM
    #12
    vtwinjunkie

    vtwinjunkie [OP] Well-Known Member

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    Thanks,

    Lastly,
    did you go with a toyota cat or aftermarket?

    Diagnosis has been slow going because I dont have a physical copy of the service manual so I am trying to do everything online with the copy I found that has everthing listed out of order (BIG PITA).

    hopefully I can find some good info on youtube, I havent checked there yet.
     
    Bulldogs129 likes this.
  13. Sep 17, 2017 at 9:18 PM
    #13
    Bulldogs129

    Bulldogs129 Don't find fault, find a remedy

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    Aftermarket cat- Autozone has a direct fit or one that you cut & weld. I bought the direct fit for somewhere around $150. Just be careful taking off the bolts. Use Kroil or some real good rust penetrating lube. Exhaust bolts are known to be trouble!!
     
  14. Sep 17, 2017 at 9:23 PM
    #14
    scocar

    scocar Treat the cause, not the symptom

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    How many miles on your truck?

    The upstream air fuel sensor failing at about 150k on the v6 is fairly common. I replaced with a denso I found on an eBay store, don't have that info handy right now, and not sure it would be the same for your 4 banger. If you replace it yourself, be sure to have a die handy to clean up the studs, and some new lock nuts.
     
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  15. Sep 17, 2017 at 9:36 PM
    #15
    Bulldogs129

    Bulldogs129 Don't find fault, find a remedy

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    Bullseye...my '02 3.4L new denso upstream was $150-175, purchased at O'reillys auto parts.
     
    Last edited: Sep 17, 2017
  16. Sep 17, 2017 at 9:37 PM
    #16
    Fstrnyou

    Fstrnyou Well-Known Member

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    My 2.4L Denso upstream was $98 on Amazon
     
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  17. Sep 17, 2017 at 9:46 PM
    #17
    Fstrnyou

    Fstrnyou Well-Known Member

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  18. Sep 17, 2017 at 9:52 PM
    #18
    koditten

    koditten Well-Known Member

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    Reserected from the dead.
    I just got chasing down a PO420 code. Mine, the issue was the gasket for the rear O2 sensor. Its been a week so far with no code thrown. Before, it would trip every day.

    Blows my mind a $1 gasket could cause that much of a headache.
     
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  19. Sep 18, 2017 at 7:57 AM
    #19
    vtwinjunkie

    vtwinjunkie [OP] Well-Known Member

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    I think I am going to order new gaskets for the cat and take it off this weekend to have a look.
    mine is a 2.7 4 cyl
     
  20. Sep 18, 2017 at 7:57 AM
    #20
    vtwinjunkie

    vtwinjunkie [OP] Well-Known Member

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    I have a 2002 2.7 4cyl with 212k miles
     

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