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rear o2 sensor - DONE!

Discussion in '1st Gen. Tacomas (1995-2004)' started by bowyer2002, Feb 26, 2011.

  1. Feb 26, 2011 at 4:55 PM
    #1
    bowyer2002

    bowyer2002 [OP] always tinkering

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    I just finished installing my rear o2 sensor at 167K! (did the front at 165K)
    CEL came back on :confused:.
    Living in the Missouri salt belt, the nuts were corroded down from 13mm to about 12.5mm! Unwrenchable with standard tools.:mad:

    I found out some things that may help others.

    When you consider doing this, start spraying these nuts and studs with a penetrating lube (PB Blaster, Liquid wrench, etc.) for a couple of days.

    1. Buy the sensor on line - got mine for about 60% of what the auto parts store wanted. Denso #234-4189 for the 3.4L v-6 auto.
    2. Have an angle grinder handy (or Dremel) for cutting off the 'shield' around the o2 sensor. AND (if necessary) to grind on the frozen nuts.
    3. I bought the Craftsman Bolt Out kit - and it was the the ticket to FINALLY get the frozen, rusted, corroded, @#%* nuts off!
    4. The replacement nuts are M8 X 1.25mm
    5. The connector is located under the passenger seat thru a gromet in the floor.
    6. Plug in the connector, running the male end thru the floorboard to the female end under the passenger seat.
    7. Install the gasket and new sensor into the exhaust, use anti-sieze compound on the studs and install the new 13mm nuts.
    8. by doing this myself I saved about $100 after buying the tool Bolt Out Kit.
    9. enjoy the CEL not being on anymore, increased MPG, satisifaction, and if you're old enough, maybe a beer! :D

    I will tack weld on another shield that I will fab out of expanded metal so the water, mud, salt, etc. will not collect around the new sensor like the original shield allowed.

    1 sensor.JPG
    1 sensro shield removal.JPG
    2 sensor shield  remaval.JPG
    1 corroded nuts.JPG
    1 ground nuts.JPG
    1 sensor plug location.JPG
     
  2. Feb 26, 2011 at 10:12 PM
    #2
    subtleshift

    subtleshift Noob

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    great info!

    does anyone know if you can have partially bad o2 sensors...I dont have a cel but was basically wondering if I did replace them would I get better mpg, or is it a on/off-works or doesnt work type thing?
     
  3. Feb 26, 2011 at 10:20 PM
    #3
    malander

    malander That's some tight butthole

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    All that rust is a pain in the ass. I got so pissed I just took my angle grinder with a cutting wheel and chopped up a good 8" section and to get a better angle on the bolts...but then I got really pissed and just took the grinder to the wires haha
     
  4. Feb 27, 2011 at 12:02 AM
    #4
    Yamaha Dave

    Yamaha Dave Well-Known Member

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    Hey man GREAT info! This is something on my to-do list for the Spring.
     
  5. Feb 27, 2011 at 8:16 AM
    #5
    shitroc

    shitroc Master of War

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    the thing to do would be to remove them and clean them up with an electrical contact cleaner in a spraycan, let them dry and reinstall them,you can also do this to your MAF(mass air flow sensor) you just need to be careful.
     
  6. Feb 27, 2011 at 9:44 PM
    #6
    subtleshift

    subtleshift Noob

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    cool...

    I acctually just got a coupon from the toyota dealership and their was an ad on the front that said worn o2 sensors can cause a 3.0 mpg decrease...

    prolly just marketing but I'm sure their is a hint of truth their, I might just have to take a day and see if I can't get those out w/o cutting and grinding
     
  7. Feb 28, 2011 at 6:17 AM
    #7
    bowyer2002

    bowyer2002 [OP] always tinkering

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    subtleshift - a little cutting and grinding never hurt anything :)
     
  8. Feb 28, 2011 at 6:34 AM
    #8
    nelson18matt

    nelson18matt Well-Known Member

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    nice, i just replaced an O2 sensor yesterday too, the one before the cat.

    i'm so glad i didnt have to deal w/ the rust issues you had. thank you so-cal :D
     
  9. Feb 28, 2011 at 6:37 AM
    #9
    bowyer2002

    bowyer2002 [OP] always tinkering

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    Nelson18matt -
    cool!
    the front one took me about 20-30 min, the rear one - downstream of cat, was a PITA, mostly time consuming & head scratching on how to approach the corroded nuts.
     
  10. Feb 28, 2011 at 7:03 AM
    #10
    nelson18matt

    nelson18matt Well-Known Member

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    yeah man, the front on was a piece of cake

    i didnt wait till after i was done to start drinking :D
     
  11. Feb 28, 2011 at 8:25 AM
    #11
    twfsa

    twfsa Well-Known Member

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    Great write up hope I have another truck before I have to replace mine. I will save your write up.
     
  12. Feb 28, 2011 at 8:31 AM
    #12
    ilove_taco_ma

    ilove_taco_ma Well-Known Member

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    nothing, all stock expect got a OE replacement air filter K&N.
    i definitly have to replace both 02 sensor. still scratching head on how to do it either but thank you for your write up.
     
  13. Feb 28, 2011 at 9:03 AM
    #13
    subtleshift

    subtleshift Noob

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    Well if I grind off the o2 sensor heatshield I'm pretty sure I'm gonna rip off all the heatshields attached to the body above the exhaust...stupid thing are always rattling!
     
  14. Feb 28, 2011 at 4:13 PM
    #14
    shitroc

    shitroc Master of War

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    this is true
     
  15. Feb 28, 2011 at 6:24 PM
    #15
    bowyer2002

    bowyer2002 [OP] always tinkering

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    with gas, around here just hitting $3.25/gal for 87 octane, ANY extra mileage is appreciated!
     
  16. Feb 28, 2011 at 6:30 PM
    #16
    subtleshift

    subtleshift Noob

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    in socal gas is like $3.90...
     
  17. Mar 2, 2011 at 6:37 AM
    #17
    bowyer2002

    bowyer2002 [OP] always tinkering

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    UPDATE -
    FWIW - it took me about 70 miles of driving for the CEL to turn itself off.
    I was getting worried that I hadn't totally fixed the problem and my cat$ were bad.
     
  18. Mar 2, 2011 at 3:06 PM
    #18
    StAndrew

    StAndrew Wait for it...

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    Im guessing there is no way to do this without grinding the shield off.... The cutting wouldnt be the issue, its the welding. How else can I re-attach the shield if I dont have a welder?
     
  19. Mar 3, 2011 at 6:11 AM
    #19
    bowyer2002

    bowyer2002 [OP] always tinkering

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    StAndrew -
    There are guys that have left the shield off without any problems.
    Before I had a welder, I had the local muffler shop weld some things like this (shield) for me - it was reasonable $.
    This may be an option for you too.
     
  20. Mar 3, 2011 at 8:09 AM
    #20
    vantaco

    vantaco Well-Known Member

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    do you have a link where you ordered the sensor from?

    i'm getting terrible milage and i'm thinking my front o2 is the problem

    no cel's but i get about 15.5/16 mpg
     
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