1. Welcome to Tacoma World!

    You are currently viewing as a guest! To get full-access, you need to register for a FREE account.

    As a registered member, you’ll be able to:
    • Participate in all Tacoma discussion topics
    • Communicate privately with other Tacoma owners from around the world
    • Post your own photos in our Members Gallery
    • Access all special features of the site

Any advice on changing the downstream 02 sensor?

Discussion in '1st Gen. Tacomas (1995-2004)' started by veg hed, Apr 20, 2019.

  1. Apr 20, 2019 at 7:25 PM
    #1
    veg hed

    veg hed [OP] Well-Known Member

    Joined:
    Mar 14, 2010
    Member:
    #33217
    Messages:
    326
    Gender:
    Male
    Utah
    Vehicle:
    04 Toyota TRD SR5 V6 Access Cab
    Bilstein 5100s, Toytec 620 springs, OME Dakar Leafs, ARB Bumper, Warn 8000 Winch, Grey Wire Mod.
    Well, Amazon did it again. I typed in exactly what I wanted and they sent me the wrong part. I should have done a little more research to ensure I got what I wanted.

    Anyway, I thought I ordered the upstream 02 sensor (Denso 234-9001) but I ordered the downstream sensor (Denso 234-4189). I thought no big deal, my truck has 172,000 miles on it so while I'm waiting on the upstream sensor to arrive I'll change the downstream one. It's not that easy.

    I found where it goes into the truck and plugs in under the seat. However, I cannot for the life of me see a way to get to the bolts due to a cover over the sensor. I thought it was a 12mm but maybe it's stripped? And if its stripped or rusted I see no way in getting it off without cutting involved. I searched on youtube and the forum and couldn't find a write up for this particular one.

    Also, is it even necessary to change the downstream sensor?

    Here's a picture of the cover over the sensor.

    IMG_2287.jpg
     
  2. Apr 20, 2019 at 7:29 PM
    #2
    koditten

    koditten Well-Known Member

    Joined:
    Sep 8, 2013
    Member:
    #112077
    Messages:
    14,939
    Gender:
    Male
    First Name:
    Kirk
    Central Michigan
    Vehicle:
    04 trd x-cab 4 x 4 3.4l
    Reserected from the dead.
    Bend it away. If it breaks no biggie. Most don't have that shield anymore.

    Heat the nuts red hot with a propane torch and use channel lock players to remove the rounded off nuts. Take your time. Works every time.
     
  3. Apr 20, 2019 at 7:30 PM
    #3
    thenodnarb

    thenodnarb Well-Known Member

    Joined:
    Jan 23, 2019
    Member:
    #280389
    Messages:
    236
    Gender:
    Male
    California
    Vehicle:
    2001 TRD 4x4 331k and counting
    1 vote for don't bother. return your part to Amazon. got an Amazon locker nearby? it's easy to return that way.

    i have 325k on my original downstream. apparently downstream sensors last much longer than the upstream.
     
    Area51Runner and veg hed [OP] like this.
  4. Apr 20, 2019 at 7:37 PM
    #4
    Old Swamper

    Old Swamper Tacoma World Poor

    Joined:
    Mar 26, 2019
    Member:
    #288101
    Messages:
    484
    Gender:
    Male
    First Name:
    Will
    Northern WI.
    Vehicle:
    2012 Black Tacoma TRD OR
    5100 & OME 884 AAL
    The nuts are a special nut and soft. They were like $6.00 each. Get 3 Incase you drop one and can’t find it like I did. I changed mine on my 2002 and it wasn’t that hard to do. I don’t recall the shield being a issue but it’s been a couple years since I did it.
     
    veg hed [OP] likes this.
  5. Apr 20, 2019 at 7:40 PM
    #5
    eon_blue

    eon_blue Unknown Member

    Joined:
    Mar 4, 2016
    Member:
    #180213
    Messages:
    50,387
    Gender:
    Male
    First Name:
    Ryan
    Monrovia, CA
    Vehicle:
    '04 TRD 3.4l 4x4 5sp manual Xtracab
    I cut that little shield with my angle grinder about 3/4 of the way so I could move it aside. Then just bent it back into place
     
    veg hed [OP] likes this.
  6. Apr 20, 2019 at 9:55 PM
    #6
    dweikum

    dweikum Well-Known Member

    Joined:
    Nov 3, 2018
    Member:
    #271575
    Messages:
    273
    First Name:
    Duane
    Oakland CA
    Vehicle:
    02 4WD V6 5spd SR5 TURD
    I recently changed mine on my 02, didn't have a problem getting a socket in there and taking the nuts off intact. Guess I was lucky.
     
  7. Apr 20, 2019 at 10:28 PM
    #7
    JJ04TACO

    JJ04TACO Well-Known Member

    Joined:
    Oct 12, 2013
    Member:
    #114311
    Messages:
    1,146
    Gender:
    Male
    First Name:
    Jim
    Dallas
    Vehicle:
    04 White DC/TRD
    Fox 2.5 RR front, 2.0 RR rear from AccuTune Offroad, OME Dakar Leafs, Camburg Uniball UCA's, CBI Offroad Bolt on Sliders w/kickout, Scangauge II Uniden Bearcat 880 w/ 3' Firestick on CBI antenna mount B&M Trans Cooler
    Dude, super easy with a 1/4" or 3/8 stubby ratchet. I think I used a 1/4"... Get a deep socket and slips right over the nuts and off it comes. I had zero issues and bent or destroyed nothing. I hit it with some penetrating oil after a drive and let it cool a bit. I don't even know if that was necessary. Both sensors came right off super easy. I cleaned the gasket mating surfaces and voila.

    As for Amazon, I ordered both sensors and received correct parts...

    Edit, Before unplugging the upstream sensor remove the wiring retainer that holds it to the frame first and pull it down a bit. It's easier that way.

    Sensors are pretty cheap. I did both...
     
  8. Apr 21, 2019 at 12:19 AM
    #8
    sandman8108

    sandman8108 Well-Known Member

    Joined:
    Oct 26, 2016
    Member:
    #200741
    Messages:
    92
    Gender:
    Male
    Los Angeles, CA
    Vehicle:
    2002 Tacoma V6 Double Cab TRD
    I just replaced my upstream sensor and decided not to bother with the downstream. Its not giving me any problems, so I figure when it does ill replace it. Why fix something that isn't broken right?
     
  9. Apr 21, 2019 at 12:22 AM
    #9
    eon_blue

    eon_blue Unknown Member

    Joined:
    Mar 4, 2016
    Member:
    #180213
    Messages:
    50,387
    Gender:
    Male
    First Name:
    Ryan
    Monrovia, CA
    Vehicle:
    '04 TRD 3.4l 4x4 5sp manual Xtracab
    Should only replace it if it's throwing a code, if I remember right the code I got for my rear O2 sensor was a p0136. Replaced the sensor with a new Denso one and it went away
     
  10. Apr 21, 2019 at 12:23 AM
    #10
    sandman8108

    sandman8108 Well-Known Member

    Joined:
    Oct 26, 2016
    Member:
    #200741
    Messages:
    92
    Gender:
    Male
    Los Angeles, CA
    Vehicle:
    2002 Tacoma V6 Double Cab TRD
    Thats what I decided to do. Just replaced my upstream after the p1135 code and man my truck runs like its brand new again!
     
    eon_blue likes this.
  11. Apr 21, 2019 at 12:28 AM
    #11
    eon_blue

    eon_blue Unknown Member

    Joined:
    Mar 4, 2016
    Member:
    #180213
    Messages:
    50,387
    Gender:
    Male
    First Name:
    Ryan
    Monrovia, CA
    Vehicle:
    '04 TRD 3.4l 4x4 5sp manual Xtracab
    Good to hear, did you go with a Denso sensor? If there's one thing Toyotas are finicky about its sensors...Denso is OEM for Toyota sensors and you hear a lot of issues stemming from people putting in other brands like Bosch and the like
     
  12. Apr 21, 2019 at 12:32 AM
    #12
    sandman8108

    sandman8108 Well-Known Member

    Joined:
    Oct 26, 2016
    Member:
    #200741
    Messages:
    92
    Gender:
    Male
    Los Angeles, CA
    Vehicle:
    2002 Tacoma V6 Double Cab TRD
    Ya I went with OEM after reading everybody suggestions. So far so good
     
    eon_blue likes this.
  13. Apr 21, 2019 at 1:32 AM
    #13
    Reh5108

    Reh5108 Well-Known Member

    Joined:
    Feb 18, 2013
    Member:
    #97832
    Messages:
    4,849
    Gender:
    Male
    First Name:
    Ryan
    Idaho
    Vehicle:
    2004 SR5 4X4 2.7L Extra Cab
    OME lift, 4x sliders, Demello rear bumper, custom front bumper, Engo 9000lb winch
    I forgot I used to have that shield. I remember it being a pita to change the o2 sensor because of it. I just cut it off.
     
    veg hed [OP] likes this.
  14. Apr 21, 2019 at 6:19 AM
    #14
    1997tacomav6

    1997tacomav6 V6 5sp,RegCab,TRD Supercharger,2"pulley,meth, 660k

    Joined:
    Oct 5, 2013
    Member:
    #113940
    Messages:
    8,432
    Gender:
    Male
    First Name:
    John
    Denver
    Vehicle:
    97 reg cab, v6 5sp 300hp supercharged, Methonal Injection, 660,001 plus miles, Original Owner
    V6 5sp,RegCab,TRD Supercharger, 2" pulley, methanol injected AC TRD supercharger,(MUST DO) TRD supercharger ported, rebuilt 3 times over 500,000 miles, every 125,000- 150,000 needs rebuild Projector headlights HID 5 speed manual Amsoil for all drive train Smaller 2” pulley,(300hp) (MUST DO) 2004 DESNO fuel injectors, zero ping ping, 2004 side door mirrors Dick Cepek Rims, Michelin tires LTX, ( that last 100,000 miles) Now running Dynopro ATM mud and snow tires KN cold air intake Cat back exhaust with ss exhaust tip, Raised exhaust tail pipe to 2" below body line Optima*dry cell battery,red top Alpine sirius radio, 200 watt amp, focal is165 split door pod speakers Focal door speakers Subwoffer behind seat Viper alarm, Electric Locks Dark tinted windows, 4runner bucket seats, Tacoma Rubber floor mats TRD fender extenders, Bilstien shocks chrome push bar, chrome nerf bars, add a leaf for rear springs trailer iv hitch, electric brake control, Drilled slotted brakes, High carbon steel (MUST DO) EBS green stuff 7000 series pads(MUST DO) TRD engine oil cap TRD stick shift, Rear sliding window 2002 4Runner functional hood scoop cut into Tacoma hood, 4Runner dual overhead map light Gentex Auto dim + Compass + Temp, garage,rearview mirror Corbeau bucket seats Snow Methonal kit stage 2 Champion 3 core aluminum radiator Linex bed liner
    I would definitely replace both at the same time. These sensors tell your computer the
    most critical information for your engine to run its best especially if you have a lot of miles
    on them and stay with DENSO.
    They get plugged up with carbon and dirt over time reducing efficiency.

    WD40 and a socket the nuts came right off for me.
     
    JJ04TACO likes this.

Products Discussed in

To Top