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P0125 Code after 02 Sensor Replaced!

Discussion in '1st Gen. Tacomas (1995-2004)' started by goomba, Oct 10, 2011.

  1. Oct 10, 2011 at 6:14 AM
    #1
    goomba

    goomba [OP] It is a Fluid Situation

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    I Have a 96 Tacoma 4x4 v6 and I have been trying to find out what is causing this code(p0125). I have replaced valve cover gaskets(not because of code), 02 sensors(it turned out to be a completely clogged cat), d-clogged cat and then replaced fuel filter. I did also notice that the PCV valve is leaking oil into the throttle body, and i will be replacing it soon. Also, my fluid temp, when warm, will reach 190 then drop to 184-187. If you need anymore info I have my own scanner. I have tried to search for this code after people replaced there 02 sensor and found nothing.
    Thanks.
     
  2. Oct 10, 2011 at 8:19 AM
    #2
    DblCabMN

    DblCabMN Well-Known Member

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  3. Oct 10, 2011 at 11:12 AM
    #3
    goomba

    goomba [OP] It is a Fluid Situation

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    I got all of my parts from the near by Toyota dealership.
     
  4. Oct 10, 2011 at 12:14 PM
    #4
    DblCabMN

    DblCabMN Well-Known Member

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    Right - so they sold you a Denso O2 sensor then? Not a BOSCH or other manufacturer right? Check your receipt and make sure, these trucks are picky when it comes to O2 sensors.

    Also - which O2 did you replace? Front or rear? (closest to the engine or closer to the muffler)

    Double also: If you bought from the Toyo dealer - you most likely paid way to much for the part - again, check your receipt, then check

    http://www.urdusa.com/More-Products.../index.html?osCsid=dd1c7auaadcmaiu2k1u453mul4

    for just about the best price on the correct O2 sensor(s). Return your Toyota one saying it's defective after getting your new one from URD in.
     
  5. Oct 10, 2011 at 3:16 PM
    #5
    goomba

    goomba [OP] It is a Fluid Situation

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    I have denso's yes, and I have replaced both. I have had them for a coupple months. :/
     
  6. Oct 10, 2011 at 3:45 PM
    #6
    DblCabMN

    DblCabMN Well-Known Member

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  7. Oct 10, 2011 at 7:30 PM
    #7
    goomba

    goomba [OP] It is a Fluid Situation

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    I took a hammer to the insides. Idk what it is called, but there is nothing inside of the cat at the moment.
     
  8. Oct 10, 2011 at 7:59 PM
    #8
    Tacoma Mike

    Tacoma Mike 42 Year Toyota Master/ASE Master Tech.

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    You more than likely have a bad a/f sensor.

    Bad a/f sensor will throw a p0125 code in earlier Toyotas

    Once you fix that the check engine light will come back on for a cat problem.

    Your temp seems to ok a this point.
     
  9. Oct 11, 2011 at 5:47 AM
    #9
    goomba

    goomba [OP] It is a Fluid Situation

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    I am kinda confused i thought the a/f sensor was the front 02 sensor. Or is it the one connected to the air box.
     
  10. Oct 11, 2011 at 1:43 PM
    #10
    Tacoma Mike

    Tacoma Mike 42 Year Toyota Master/ASE Master Tech.

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    you are correct.
    A/F (air fuel ratio) is the front sensor and the 02 is the rear.

    They play mumbo jumbo with the sensor names.

    Up by the box you have various sensors named differently depending on the years they were built.

    Open or short in A/F sensor circuit
    A/F sensor
    ECM.

    I know it's a bit confusing with insufficient coolant temp and it does work with the ecu to work for closed loop.

    Take a step back and remember what you did. The only thing you did was change sensors. You had no codes for this before the change

    I'm not there so i can't check it for you but just go back and recheck your work to make sure you have good connections and no broken wires.
    i know this might sound stupid but if you don't find anything and had your old sensors i would throw them back in.

    Whats the time frame between replacing the sensors and the code ???
     
  11. Oct 11, 2011 at 4:17 PM
    #11
    goomba

    goomba [OP] It is a Fluid Situation

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    At first I had 2 codes i think they were p0130 and po133 saying both sensors were bad. Replaced them. Then i dumped the cat, got five codes, p0130, p0125 then others that i forget. Then i replaced the fuel filter got the p0125 code left and it keeps coming back. I just cleaned my MASS AIR FLOW sensor and replaced my PCV valve, and still code comes up. I replaced PCV valve coz it was leaking oil into the throttle body. But i will check my wire connections. and get back with you.
     
  12. Oct 11, 2011 at 5:35 PM
    #12
    goomba

    goomba [OP] It is a Fluid Situation

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    I checked my 02 sensors on the exhaust, and where they plug in on my transmission. The wires are plugged in good and connections are good and clean. The 02 sensors are sealed well on the exhaust. What do you think I should do next?
     
  13. Oct 11, 2011 at 6:24 PM
    #13
    Tacoma Mike

    Tacoma Mike 42 Year Toyota Master/ASE Master Tech.

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    If you read my prev post I suggested putting your old sensors back in if you didn't destroy them. Thats the only thing you did and now your getting this
    p0125 code.

    Another thing i would do if you didn't is disconnect the battery for a time so the ecu can get a fresh start.
    the two codes you mentioned are for the same sensor.

    So something is not right here.

    I hope you got the right sensors for the right spot.

    how long did this take to show up ??
     
  14. Oct 11, 2011 at 6:39 PM
    #14
    goomba

    goomba [OP] It is a Fluid Situation

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    I tossed the old sensors. :/ I had the parts guy look up the part via my vin #, and you cant mix up front from rear. the rear 02 sensor cord is not long enough to work in the front.
     
  15. Oct 11, 2011 at 6:41 PM
    #15
    Tacoma Mike

    Tacoma Mike 42 Year Toyota Master/ASE Master Tech.

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    Was this code immediate after replacement ??
     
  16. Oct 12, 2011 at 6:09 AM
    #16
    goomba

    goomba [OP] It is a Fluid Situation

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    Yes it was. I may change my thermo and my coolant temperature sensor next. Would that be a good idea?
     
  17. Oct 12, 2011 at 3:39 PM
    #17
    Tacoma Mike

    Tacoma Mike 42 Year Toyota Master/ASE Master Tech.

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    I think your going in the wrong direction myself. It's showing 190 on the scan tool you said so that's plenty hot enough.

    Sorry I can't be more help but at this point you need some wiring checks. i still think you have a bad AF sensor or wiring issue. Like i said it's a mis represented code and does not reflect coolant temp for that year.

    It was immediate after sensor replacement. So don't you think that's where you should go?

    Good luck..........................
     
  18. Oct 13, 2011 at 5:57 AM
    #18
    goomba

    goomba [OP] It is a Fluid Situation

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    Thanks for the help.
     
  19. Oct 13, 2011 at 6:40 AM
    #19
    Tacoma Mike

    Tacoma Mike 42 Year Toyota Master/ASE Master Tech.

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    Your welcome

    Hope you get it straightened out. :wave:
     
  20. May 31, 2012 at 10:32 AM
    #20
    goomba

    goomba [OP] It is a Fluid Situation

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    Found out it was a wrong 02 sensor.
     
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