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  1. #1
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    O2 sensor question

    I replaced an O2 sensor on my TJ in an attempt to fix a check engine light. The light stayed on, and I later found that the wiring harness to the O2 sensor was crushed, and all 4 wires were exposed, shorting to ground, and each other. I've fixed the harness, but the sensor still shows as bad.

    My question is, if the wires to the sensor shorted, is the sensor shot, and in need of replacement?

    Sent from my Nexus 4 using Tapatalk
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  2. #2
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    Did you reset the PCM?

    What code are you getting?
    "Never look down on anybody unless you're helping him up" - Jesse Jackson

  3. #3
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    Re: O2 sensor question

    Current Fault Log
    ------------------
    P0161: O2 Sensor Heater Circuit (Bank 2 Sensor 2)

    I replaced the sensor, and ran like that for a couple of weeks before finding the wires were exposed and all shorting together. I'm thinking this may have destroyed the sensor, and it needs to be replaced again.
    Or I could have yet another wiring issue somewhere...
    My 2005 Wrangler Build Thread

    “He who is without oil shall throw the first rod.” -Compressions 8.7:1

  4. #4
    Terry, if the wiring damage is far enough from the sensor , a wiring repair should fixit with proper insulation like a shrink tubes to cover the exposed wires after solder. Make sure the wiring is correct , not swapped in the wrong position. You will need to do a hard reset with the use of a scan tool or a battery disconnect to clear the PCM. If the condition still exist after the reset, there might be more going on with that issue , possibly a bad sensor , more wiring issues or the PCM. Sent from my iPad using Jeepz
    Confucious says: Don't eat the snow where the huskies go!

  5. #5
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    Re: O2 sensor question

    I'm using a scan tool (torque phone app and a bluetooth ODBII reader), and resetting the fault codes after each round. I'll look at it again to make sure that I didn't mix up the wires when crimping things back together.

    Thanks guys. I did use good butt connectors with heat shrink tubing. The break was on the back of the engine, so it was a bear to get to. I'm going to try swapping in a new O2 sensor.
    My 2005 Wrangler Build Thread

    “He who is without oil shall throw the first rod.” -Compressions 8.7:1

  6. #6
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    Re: O2 sensor question

    I have beat my head over this issue, and I still can't get it. The wiring harness for O2 sensor 2 bank 2 was crushed between the body of the Jeep and the engine. Here is what I've done:

    • Replaced the O2 sensor
    • Cut and cleaned up the broken wires and used crimp on butt connectors to repair the breaks
    • Replaced the O2 sensor again
    • Cleared fault codes (about 20 times).
    • Cut out the butt connectors, and soldered the connections, using heat shrink tubing.


    I'm still getting the original P0161 (after about 2 minutes of idling). I'm pretty sure that the wires aren't crossed, however the wiring harness has two brown wires, so I don't want to rule out that. I feel like I need to use my multimeter to verify things, but I'm not sure what I should look for.

    Any ideas guys?
    My 2005 Wrangler Build Thread

    “He who is without oil shall throw the first rod.” -Compressions 8.7:1

  7. #7

    Re: O2 sensor question

    when you change the wiring, you change the resistance the computer reads from the o2 sensor. it will put your readings out of the range allowed by the computer. i have heard of people soldering the wires back together to get the resistance closer to normal but i have also heard of people having a heck of a time getting that light to turn off after having the wires get messed up so i don;t know what to say works and doesn't. i know the butt connectors are 99% of the time a no go on o2 sensor wiring repairs.
    no more jeeps at this time. next time it will be a cj with a v8

  8. #8
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    Re: O2 sensor question

    Here's what the code means:
    161 Oxygen sensor heater element not working properly (this device helps to reduce emissions more quickly)

    My understanding is that the heater in the O2 sensor isn't working. I'm going to have to take another look at the wiring tonight.
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  9. #9
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    Quote Originally Posted by TerryMason View Post
    Here's what the code means: 161 Oxygen sensor heater element not working properly (this device helps to reduce emissions more quickly) My understanding is that the heater in the O2 sensor isn't working. I'm going to have to take another look at the wiring tonight.

    Did you buy a NTK of OEM sensor?

    Are you sure you got the correct sensor? Each position is a different part number.


    P0161 is the heater element not functioning or heating the sensor to a prescribed temp(res)within the prescribed time.
    Part of the circuit is your exhaust. The sensor comes pre coated with a perma-lock. Be sure this doesn't get all over the sensor or inhibit metal to metal contact between the O2 and the exhaust.

    Did the new O2 work for a while or never?

    After 2min?.... Look for an exhaust leak at or before the O2
    Blocked or empty CAT
    "Never look down on anybody unless you're helping him up" - Jesse Jackson

  10. Re: O2 sensor question

    dont tj's have a fuse for the oxygen sensor heater. if so check in the fusebox under the hood.

  11. #11
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    Re: O2 sensor question

    I remember you mentioning that the OEM sensors were better - both of the sensors I've tried have been NTK.

    The entire problem started when I plowed into some thick mud. I came down pretty hard, and that's when the wires on the harness got cut. It's possible the exhaust got tweaked as well.

    The O2 sensor worked for about 30 miles if memory serves, before the light came on again. Now when I reset the code a new one comes back in about 2 minutes.

    I'll go and look for more exhaust leaks tomorrow.
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    “He who is without oil shall throw the first rod.” -Compressions 8.7:1

  12. #12
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    Quote Originally Posted by TerryMason View Post
    I remember you mentioning that the OEM sensors were better - both of the sensors I've tried have been NTK. The entire problem started when I plowed into some thick mud. I came down pretty hard, and that's when the wires on the harness got cut. It's possible the exhaust got tweaked as well. The O2 sensor worked for about 30 miles if memory serves, before the light came on again. Now when I reset the code a new one comes back in about 2 minutes. I'll go and look for more exhaust leaks tomorrow.
    Shop vac blowing up the tailpipe will help you find the leak.
    "Never look down on anybody unless you're helping him up" - Jesse Jackson

  13. #13

    Re: O2 sensor question

    thats an awesome way to look for leaks. i will remember that
    no more jeeps at this time. next time it will be a cj with a v8

  14. #14
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    Re: O2 sensor question

    I'm really frustrated by this problem. I just can't get that check engine light off. I'm currently sitting on a P0058 (O2 SENSOR 2/2 HEATER CIRCUIT HIGH) error.

    Here's what I've done


    • Repaired the cut O2 sensor harness wires several times. They are currently soldered and seem to have a really good connection.
    • Replaced the O2 sensor 3 times. The current sensor is MOPAR from the dealer


    I've got a scanner, and I can monitor all my O2 sensors - the first three all fluctuate between .2 and .8, but this O2 sensor just sits pegged at 1.75 - never any fluctuation.

    Anyone have any thoughts? I'm unable to find any fuse for the O2 sensor.
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    “He who is without oil shall throw the first rod.” -Compressions 8.7:1

  15. #15

    Re: O2 sensor question

    Have you checked the voltage going to the sensor? Disconnect the sensor and see if your getting 12v on the power lead. Anything less and it's a power problem.




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  16. #16
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    Re: O2 sensor question

    I've got four wires on the O2 sensor - two white, a gray, and a black. Do you know what voltages I should have on them?

    I'll cut an old O2 sensor and read the voltages later today.
    My 2005 Wrangler Build Thread

    “He who is without oil shall throw the first rod.” -Compressions 8.7:1

  17. #17

    Re: O2 sensor question

    Your hot should be one of the white wires, possibly one is striped. You might also check the ground wires for a voltage drop reading. A max voltage reading of 0.250 volt indicates a bad (shorted) wire connections. Do this with key on and reading must be done when engine is hot and cold. They readings should be the same.




    Rules while in my Jeep....

    Hold on
    Don't touch buttons!
    Quit Screaming!
    Don't puke!






  18. #18
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    Re: O2 sensor question

    Thanks for the help guys. I spend some time with my multi-meter today, and have some voltage readings.

    O2 Sensor color Harness color Key on voltage Cold voltage Hot voltage
    White Black Common / Ground Common / Ground Common / Ground
    White Brown 1.8mv 11-13mv 7-10mv
    Black Brown w/Stripe 4.17 4.14 4.13
    Gray Blue 2.5 2.51 2.51

    When I switch to continuity check on my multimeter, ground the negative probe, and connect to the second white lead (Brown harness wire), I hear a faint continuity buzz.

    Should one of these four leads be a +12v?[TABLE="class: grid, width: 949, align: center"]
    Last edited by TerryMason; 01-25-2017 at 03:57 PM.
    My 2005 Wrangler Build Thread

    “He who is without oil shall throw the first rod.” -Compressions 8.7:1

  19. #19

    Re: O2 sensor question

    no idea here. you are outside my range of knowledge
    no more jeeps at this time. next time it will be a cj with a v8

  20. #20
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    "Never look down on anybody unless you're helping him up" - Jesse Jackson

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