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Aftermarket sensor?

Discussion in '1st Gen. Tacomas (1995-2004)' started by kse, Jan 4, 2017.

  1. Jan 4, 2017 at 4:09 PM
    #1
    kse

    kse [OP] Active Member

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    Albert
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    Hey everyone,

    I need some help.

    '02 V6 2WD Auto
    73K.. :)

    My CEL light came on so I bought a scanner and got the P0420 code. Searched a ton of threads on here, figured out what the code meant, then took a look under the truck to visually inspect the sensors. It was after work, dark, and all I had was the light on my phone.

    What I found was the downstream sensor wiring harness completely mangled and almost torn all the way through (see picture attached).

    My question is, this sensor doesn't look like the Denso 234-4189 I need (no flange/bolt set up), so what are my options? It looks like the previous owner(s) had a shop weld a new piece of pipe in place of the old, and either screwed or welded a new sensor in (again, it was dark, and I didn't get a really good look so I'm not 100% sure). Looking at the harness, it looks like they secured the wiring and THEN screwed the sensor in, mangling and eventually compromising the harness--right?

    I was hoping to buy the Denso 234-4189 on Amazon, but I'm holding off now because I'm stuck.

    Thanks,

    -Albert

    234-4189.jpg
     
  2. Jan 4, 2017 at 4:28 PM
    #2
    KdF

    KdF Old Rednek Type

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    1st thing "I" would do is fix the wires if feasible and unhook the battery for 15 min to see if the code goes away.
     
  3. Jan 4, 2017 at 4:39 PM
    #3
    cruiserguy

    cruiserguy Well-Known Member

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    Omg, that undercarriage.... Drool.... Yeah that is definitely not the original sensor. They cut out the original sensor mount, the bung, and replaced with that deal. Bummer. You can have a shop redo it with a Toyota style bung and replace with a true oem Denso sensor. That'll be your best bet I imagine with the ECM throwing an MIL.
     
  4. Jan 4, 2017 at 4:42 PM
    #4
    kse

    kse [OP] Active Member

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    I did try to clear the code on the reader before visually inspecting the sensor. It "failed" to clear the code (which lead me to look under the truck).
     
  5. Jan 4, 2017 at 4:42 PM
    #5
    KdF

    KdF Old Rednek Type

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    The wires "may" be the culprit tho........
     
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  6. Jan 4, 2017 at 4:47 PM
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    chaosrob

    chaosrob Well-Known Member

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    Makes sense to me. If the wires are frayed try to shore them up THEN reset the code
     
  7. Jan 4, 2017 at 5:20 PM
    #7
    kse

    kse [OP] Active Member

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    I will try that in the next couple days and post an update. Any tips on how to shore them up? I literally do not know what to use.
     
  8. Jan 4, 2017 at 5:57 PM
    #8
    KdF

    KdF Old Rednek Type

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    If they are exposed and frayed, the best thing I would do is cut, solder and shrink wrap each. then wrap it all to hell with electrical tape.
     
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  9. Jan 4, 2017 at 5:59 PM
    #9
    cruiserguy

    cruiserguy Well-Known Member

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    Yep.
     
  10. Jan 5, 2017 at 10:48 AM
    #10
    kse

    kse [OP] Active Member

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    Took a quick look this morning and the wires didn't look frayed. I might just have to unplug and take it out to look closer.

    If the wires look OK, how would I go about finding a replacement sensor that fits this sensor mount? Would Denso have one, or am I stuck with something else?

    Thanks for helping the newb. FWIW, I'm all for being hands on and working on my own 'taco. I even watched about 30min worth of youtube vids on soldering last night. Looks easy-peasy!
     
  11. Jan 5, 2017 at 12:02 PM
    #11
    KdF

    KdF Old Rednek Type

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    Disconnect it then Unscrew it if possible and take it to a parts store and see if they can match it. Usually they come with the wires, you may have to rig it to work.
    Always looks easy except for that third hand you need to hold the wires together as you solder. Then you look down and realize that you forgot to put the shrink wrap on 1st.
     
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  12. Jan 5, 2017 at 12:07 PM
    #12
    kse

    kse [OP] Active Member

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    Thanks, I was just told the same thing by someone at work this morning.

    And LOL about the 3rd hand and shrink wrap. I saw all of that and decided that if I do purchase a soldering gun, I'll go ahead and grab a kit, with the wire holder. The right tools always make a difference!
     
  13. Jan 8, 2017 at 1:07 PM
    #13
    kse

    kse [OP] Active Member

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    Update:

    The wires looked OK. In the process of removing the sensor, I noticed the washer between the sensor and the bung had some play in it. I was able to resecure it, but not before pulling the sensor out to have a look.

    Honestly, I'm not sure if it's bad. My scan tool still wasn't able to clear the code. And on top of that, it's giving me "P0420" and "P0420 P"

    I searched the second code but all I found was the normal P0420. I finally unplugged my battery, waited, and rehooked everything back up; sensor connector, sensor, and finally the battery.

    The code is gone. Anyone know wth p0420 p is? I took some photos and a vid of what the sensor looks like.

    IMG_3908.jpg
    IMG_3904.jpg
    IMG_3905.jpg
    IMG_3907.jpg
     
  14. Jan 8, 2017 at 1:28 PM
    #14
    mlcc

    mlcc Well-Known Member

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    P0420 is a cat code and its probably whats at fault, people have done those style sensor because its easier to remove. You can test the sensor with an ohm meter.
     
  15. Jan 8, 2017 at 1:50 PM
    #15
    kse

    kse [OP] Active Member

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    To add more information to all of this, I drive about 5 miles to work, one way. I would say about 80% of my driving is short distances. Could that be contributing to this?

    I'm about to drive around to see if the code comes back. In the meantime, here's a quick vid of what the sensor looks like https://youtu.be/oLw6S9yIoBM
     
  16. Jan 8, 2017 at 2:06 PM
    #16
    smmarine

    smmarine Well-Known Member

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    P0420 is an emissions code. Can be a lot of things, such as bad rear o2, bad cat. Your Cat and o2 sensor are aftermarket. The factory cat bolts in, that is welded. These trucks are very sensitive emissions wise, and do not like aftermarket cats. Add an aftermarket o2 sensor into the mix, and that's probably why your CEL is on.
     
  17. Jan 8, 2017 at 3:23 PM
    #17
    mlcc

    mlcc Well-Known Member

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    P0420 is cat effiency below threshold, the ecm is seeing erratic voltage when its supposed to fairly steady voltage in the rear and erratic in the front. If its erratic in the rear the cat is not doing its job properly and the only way to fix that is replace the cat.
     
  18. Jan 8, 2017 at 4:06 PM
    #18
    Thad

    Thad Well-Known Member

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  19. Jan 9, 2017 at 3:23 AM
    #19
    NightProwler

    NightProwler Well-Known Member

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    Looks like a Bosch sensor. I had the same sensor up front, but oem sensor in back. So they must've changed the front at some point. I replaced the front with a Bosch As well as a denso rear and it's held up just fine so far no issues. This was after complete custom exhaust too with only 1 high flow cat vs original oem duals. I wouldn't stress replacing the whole thing to make it accept a denso tho. If it comes to that.
     
  20. Feb 12, 2017 at 9:02 PM
    #20
    kse

    kse [OP] Active Member

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    Never got a chance to post this earlier today. As luck would have it, just when I thought I was out of the woods, the light came on. For some reason, i couldn't get my scanner to bring the code up to see what it was. I then accidentally cleared the code lol.

    So now I'm waiting.
     

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