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air-fuel ratio sensor connection broken

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by leemcgee, Aug 2, 2016.

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  1. leemcgee

    leemcgee Junior Member

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    II
    Good morning, I have been debugging DTC codes 2237/2238 and what sounds like detonation in a failed catalytic converter in my old 2007 Prius (375,000 miles!), I just removed the wipers and cowl yesterday to look at the air/fuel ratio sensor connection, and my connector appears to be melted somewhat, sides of the connector show signs of melting I am guessing that there is a connection problem stemming from this and the root cause of my DTC codes.

    Can the four wires each side be removed so I can get the connector out to look at it carefully?

    Can the bad connector be removed and the four wires be simply spliced together to get the air/fuel sensor working again? I did note that the colors of the wires going in are NOT the same as the colors of the wires going out.

    Will any cheap four wire connector work? Again, which wires connect with with wires?

    Am hoping that there might be some help here before I do something stupid! Am not touching a thing until I hear back from this august group.

    Thanks, Lee
     
    #1 leemcgee, Aug 2, 2016
  2. ChapmanF

    ChapmanF Senior Member

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    Just seeing signs of melt/distortion around the outside of a plastic connector shell might make me a little suspicious, but it's not necessarily any kind of smoking gun about the quality of the electrical connections inside the connector. So, yes, it might make me look, but any further conclusions would depend on what I saw when I looked.

    If it were me, I would go feed techinfo.toyota.com a $15 cookie right about now (which is good for two days), and start by finding those exact DTCs in the repair manual, and following the page numbers next to them to find the actual steps for diagnostic workup. Probably they will involve connecting a voltmeter or scope and watching the change of signal under certain conditions, and then you'll have a better idea whether the problem seems like the sensor itself, or a connector, or something else.

    All your questions about the connectors, how they disassemble, how to remove and insert the wire terminals, will be answered for you in the wiring diagram manual, also yours on techinfo for your same $15. It will also contain the part number for that connector shell, if you want to just pick up a new non-melted one and go the easy way. They're not very expensive, the real connector shells, and they're well designed and sealed for the underhood environment. You probably won't beat them with any generic replacement you can find (plus you would work harder at cutting wires, attaching different terminals, etc.).

    -Chap
     
    #2 ChapmanF, Aug 2, 2016
  3. leemcgee

    leemcgee Junior Member

    Joined:
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    Location:
    Mount Aukum CA
    Vehicle:
    2007 Prius
    Model:
    II
     
    #3 leemcgee, Aug 2, 2016
  4. leemcgee

    leemcgee Junior Member

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    Location:
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    Vehicle:
    2007 Prius
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    II
    Thank you very much Chap for that great information, I was unaware of that site and how it worked. Right now I suspect that that "melt" is just 9 years of detritus, eg oil or other buildup, on the connector and am about to find out. The exact test of whether the culprit is actually the air flow sensor will tell me soon what has happened. As I've said, I am not touching anything yet until I get a good and clear understanding of where the problem might be. Thanks Chap!
     
    #4 leemcgee, Aug 2, 2016
  5. leemcgee

    leemcgee Junior Member

    Joined:
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    Location:
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    Vehicle:
    2007 Prius
    Model:
    II
    Pardon me for not posting the follow up for two weeks I have been quite busy with work, time to update you all!

    I ran the resistance test and there is no problem with the A/F sensor, all resistances within normal range. And in the process I did indeed determine that I only had a bunch of junk on the connector after all these years, no melting at all. So in the process of disconnecting then reconnecting that connector, plus all that handling, the connection problem went away! No more 2237 or 2238 codes. The only code I get now is the darned 0420 catalytic converter failed code, plus a lot of noise whenever going up a hill and pressing the gas pedal down a lot, signs of a clogged converter for sure.

    Fortunately I live in a no-smog-test county here in California!

    Cheers and thank you all! -Lee
     
    #5 leemcgee, Aug 17, 2016
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