O2 Sensor Question

Discussion in 'Fox 5.0 Mustang Tech' started by stykthyn, Aug 30, 2013.


  1. stykthyn

    stykthyn Commander of the snuggie cultists

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    I have two different O2 sensors in my car. One is a black sleeve over the wires and has three wires, the other is a white sleeve and has four wires. I was under the impression that EECIV wiring was set up for a 3 wire sensor. My buddy put in the 4 wire when we got ready for the first fire up after the rebuild. Since then I've had a miss and my passenger bank( the one with the odd sensor) reeks of fuel. Could the four wire sensor be the culprit?
  2. madspeed

    madspeed Colonel Mustard Mod Dude Founding Member

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    what year, the 87?
  3. stykthyn

    stykthyn Commander of the snuggie cultists

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    yes. its an 87
  4. madspeed

    madspeed Colonel Mustard Mod Dude Founding Member

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  5. madspeed

    madspeed Colonel Mustard Mod Dude Founding Member

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    looks like you have 1 wrong sensor, as per the diagram they are both 3 wires
  6. stykthyn

    stykthyn Commander of the snuggie cultists

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    sho nuff. 3 wires it is. that will likely nix my rich condition, hopefully the stumble is a by product of that as well.
  7. madspeed

    madspeed Colonel Mustard Mod Dude Founding Member

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    most likely
  8. mikestang63

    mikestang63 Mustang Master

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    To the best of my knowledge you need the 3 wire. I replaced on of mine about a year ago. The 4 wire O2 are grounded through the harness, while the 3 wire O2 sensors ground through the body.

    Wiring is as follows
    gray wire is the ground
    black is signal
    white wires are heater

    If you tried to use the 4 wire on a three wire car, you don't have a ground. The connector will actually plug in, but the mating connector on the car harness will not provide a ground and you can fry your EEC.

    Are you getting a CEL?
  9. stykthyn

    stykthyn Commander of the snuggie cultists

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    not for the O2s which is why I never questioned it.
  10. madspeed

    madspeed Colonel Mustard Mod Dude Founding Member

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    Pull codes yet? Looks like you found the problem, but i'd run your codes for sure. At least run them after you swap in the correct sensor and clear them
  11. stykthyn

    stykthyn Commander of the snuggie cultists

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    yes, all my codes were for my smog pump and charcoal canister which have been removed. Had one for the TPS but that has been fixed. I plan on replacing both sensors, will pull codes and report back after that.
  12. mikestang63

    mikestang63 Mustang Master

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    Pretty sure the part #
    Bosch 13942
  13. Grabbin' Asphalt

    Grabbin' Asphalt Mustang Master

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    at @-zone the direct fit(shorter wire harness) was more $$$ than the universal o2(longer wire). I used a tie strap no issues and save a little $$
  14. stykthyn

    stykthyn Commander of the snuggie cultists

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    I saw a 3 dollar difference between the universal and the direct fit. one was 36 and the other 39.
  15. Grabbin' Asphalt

    Grabbin' Asphalt Mustang Master

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    Now you know, .......and knowing is 1/2 the battle, ...G.I Joe!!!:nice:

    That's $6 towards gas, nice combo meal after the install or ice cream plus at Sonic!!!!
    stykthyn likes this.
  16. stykthyn

    stykthyn Commander of the snuggie cultists

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    I'm all about a double whopper. add bacon.
  17. Grabbin' Asphalt

    Grabbin' Asphalt Mustang Master

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    D@mn I'm gettin' hungry now!!!
  18. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    The 4 wire sensors are for the 4 cylinder cars. The extra wire is a ground, and I don't know if it is the sensor ground or the heater ground. You need 2 good O2 sensors with the 3 wire setup that the 5.0 Fox Mustangs use.

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