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Front oxygen sensor question resetting code

Discussion in '1st Gen. Tacomas (1995-2004)' started by 02pretaco, Sep 15, 2008.

  1. Sep 15, 2008 at 7:19 PM
    #1
    02pretaco

    02pretaco [OP] Member

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    2002 Prerunner Double Cab 2.7 4-banger. Front oxygen sensor light came on verified with Toyota. Ordered and replaced it with Denso sensor. Light was off for about 300 miles and came back on. Reset it by disco'ing the battery. Light came on again after about 300 miles. I'm aggravated at this point. Tried a couple of more times but has come on both times but after only about 50 or 60 miles. I figure if the new sensor was bad it would come on immediately and stay on as the original sensor did. It's got 110,000 miles on it...FYI. Will resetting it with a scantool be a more appropriate and permanent way to make the light go out and stay out? I haven't had the code checked out since swapping the O2 sensor but I assume that's what it is. *Note--the truck runs fine* Any advice?:confused:
     
  2. Sep 15, 2008 at 7:22 PM
    #2
    tacomaman06

    tacomaman06 Carolina Alliance: Enforcer

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    getting there....
    just a thought........what kind of air filter do you have?? its possible that the maf sensor could be dirty and causing the light to keep coming on...even with the new sensor.
     
  3. Sep 15, 2008 at 7:24 PM
    #3
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine. Moderator

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    There may have been a second code. Have it checked and get back. :)
     
  4. Sep 15, 2008 at 7:27 PM
    #4
    02pretaco

    02pretaco [OP] Member

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    Stock Toyota filter. I try to keep filters OEM. I will admit though that I do need a new one...getting dirty. It's just a little frustrating when you spend a chunk of cash on a sensor and the light is still staring me in the face. I appreciate the input!!
     
  5. Sep 15, 2008 at 7:28 PM
    #5
    02pretaco

    02pretaco [OP] Member

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    I'll have it checked out and see if there's any other/new codes.
     
  6. Sep 15, 2008 at 7:42 PM
    #6
    Janster

    Janster Old & Forgetful

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    Toyota checked the codes?

    Are you absolutely sure you replaced the right one? Perhaps the second O2 sensor is also bad?
     
  7. Sep 16, 2008 at 12:24 PM
    #7
    Bs 02 Taco

    Bs 02 Taco Well-Known Member

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    Hey man, I have an 02 2.7 that I just replaced the front o2 sensor in. The light went off after 2 starts and is still off to this day. It has made my fuel mileage better as well. Check my thread for the o2 sensor code and see if its the same problem.
     
  8. Sep 27, 2008 at 2:18 PM
    #8
    02pretaco

    02pretaco [OP] Member

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    Finally went by Autozone and had them scan my truck. Well, it appears the oxygen sensor is okay. They pulled P0440, P0441, and P0446....emissions stuff....never had that before. I just drove straight home and logged on so I haven't checked under the hood for any loose or deteriorated hoses.

    When I was having my oxygen sensor problem Toyota ran their "diagnostics" on it. I'm not sure of what all is involved in that. Do they hook up anything to the vacuum lines or anything like that? The reason I ask is possibly while Toyota were doing the diagnostics something got jacked up. Not blaming them, just saying sometimes when older rubber hoses are moved around sometimes they go to crap (dryrot and fail). I've never had these codes before.
     
  9. Sep 29, 2008 at 5:50 PM
    #9
    Monkeysuncle

    Monkeysuncle My Cat's breath Smells like Cat Food

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    My truck also had the p0440 code and the "TECH" at the local autozone said o2 sensor, I bought a can of aerosol electronic parts cleaner and cleaned the maf sensor new air filter removed the battery and a main fuse in the fuse block in the engine compartment, viola, no more check engine light, and the maf was fuzzy with dust and dirt, it should be clean and actually look like a small spring, just be careful when messing with it, it's expensive, not 700 Billion expensive but not a cheap replacement.
     
  10. Oct 12, 2008 at 10:24 AM
    #10
    02pretaco

    02pretaco [OP] Member

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    Well, the oxygen sensor is now a non issue. AutoZone can't pull that code up anymore so I am confident all is well in that department. As far as the emission codes go I think I've found the culprit. I was filling up the other day and I noticed gas dripping near the left framerail. Joy!

    Anyway, there's the rubber hose that runs from the fuel door into some sort of shorter pre-molded hose then it runs into the tank. It's hard to see in that area due to the framerail and bed but my only guess is that it's leaking at the joint between the two.

    I can only assume since the fuel system is not "airtight" anymore it's tripping the code. Anyone have any issues with this? I also noticed there is a TSB for something in the fuel system regarding leaks and since I bought the truck with about 89K on it I'm not sure if it has been accomplished. I thought perhaps this could be the problem as well.

    I'll check with Toyota tomorrow and see if they can run the VIN and see if the hose guard or whatever the TSB says (don't have it in front of me now) has been done.
     
  11. Oct 12, 2008 at 10:27 AM
    #11
    tacomaman06

    tacomaman06 Carolina Alliance: Enforcer

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    getting there....
    thats very possible. i know that if you leave the fuel cap on, but not tight, it will set off the cel.
     
  12. Oct 12, 2008 at 10:57 AM
    #12
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine. Moderator

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    1) P0446 : Evaporative Emission control system Vent control circuit
    2) P0441 : Evaporative emission control system incorrect purge flow
    3) P0440 : Evaporative emission control system

    (Found on another board)

    Vacuum Switching Valve (VSV) - Codes P0440, P0441, P0446
    There are two VSVs. One is up at the air cleaner (according to my dealer this one almost never fails) the other one (the one that does fail - wouldn't you know it) is down underneath the car beside the gas tank, and adjacent to the charcoal canister. Presumably it fails because it is more exposed to splash from the road. One clue that it is a problematic VSV is that the above 3 codes appear at the same time. This problem does not affect vehicle driveability, although it might be a problem when you go for your emissions test. Replacing this valve is not hard but it is uncomfortable because you're lying on your back looking up at the VSV (unless of course you have a hoist - which I don't) and dirt is falling on your face. You just have to pull off a short (few inches) length of tubing which obstructs access to the VSV. This tube is not clamped, you just pull it off, it is a larger diameter with a small tube branching off. Once you have pulled that off, you have a better view of the VSV. It is held by one Phillips screw, which is hard to get at. You would need a right-angle screwdriver; I don't, so I just managed to get it off by grabbing it with a pair of pliers, and turning it bit by bit. Narrow vice-grips would be good too. Feel free to do much cursing while attempting to remove screw. When the screw is removed, undo the electrical connector, and pull off the two tubes from the valve. Out with the bad, and in with the good. In my opinion the VSV is held quite firmly by the attached hoses and electrical connector. I didn't try to get that screw back in, it is just not worth the effort. You could use a cable tie to secure the VSV quite well. Reset your CEL and congratulate yourself.
     
  13. Oct 25, 2008 at 12:13 PM
    #13
    02pretaco

    02pretaco [OP] Member

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    After some more investigating I found that the small premolded (looks like a mini flex fit radiator hose) hose was leaking. Ordered it. Will swap it out. Should clear the emissions code as well.
     
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