Exhaust Having Trouble With O2 Sensors

Discussion in 'SN95 4.6L Mustang Tech' started by Tyler Hallett, Jan 17, 2014.


  1. Tyler Hallett

    Tyler Hallett New Member

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    I have a 96 and the check engine light is on and it says bank 1 sensor 2 is bad. Well I got the numbers reversed and changed bank 2 sensor 1. So I took the plug that I pulled out of bank 2 sensor 1 because it was still good, and put it in bank 1 sensor 2.. and it didn't fix my problem and the check engine light is still on. My question is... Are the front sensors and back sensors different? Or are the sensors on one side different from the others?? I appreciate any help I can get, I am pretty new to the game.
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  2. madspeed

    madspeed Colonel Mustard Mod Dude Founding Member

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    Front and back connectors should be different and thats the reason for multiple part numbers. Did you clear the codes after screwing with them?
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  3. wmburns

    wmburns SN Certified Technician

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    Rarely will you get a DTC code that "says" that an O2 sensor is bad. Most ppl look at the DTC code and see the word "O2" and "assume" that the O2 sensor is bad. It's only after replacement that the real trouble shooting begins.

    It would help us to help you if the full DTC codes were posted.

    Note also that the back number #2 sensor is used to monitor the Cats. A problem with either #2 sensor will not cause a drivability issue.

    For the Mustang, the #1 and #2 O2 sensor are the same. From the factory, the color of the O2 pig tail is different. Hence the the different part #'s.
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  4. Tyler Hallett

    Tyler Hallett New Member

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    The code says o2 circuit- bank 1 sensor 2. And yes we cleared the codes after changing that sensor and it didn't fix my problem at all and after driving it for a while the light came back on. So are the connectors the only difference or do the different sensors serve different purposes?
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  5. wmburns

    wmburns SN Certified Technician

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    The front O2 sensors control Air/fuel ratios. A problem with the fronts will affect how the motor runs.

    The rear O2 sensors MONITOR the cats. A problem with the rears will NOT affect how the motor runs.

    The replacement O2 sensors are the same for the fronts and back as well as left and right. The after market is not concerned with the color of the factory pigtail.

    Sooooo have you concluded that the O2 sensor itself isn't the problem since the DTC code is unchanged?

    It ties the hands of the ppl trying to help you when you don't post the full DTC codes. However, if this is a circuit fault DTC code, the usual causes are:
    • Water in the connector
    • blown fuse
    • Burned, pinched, chaffed wiring harness.
    • bad PCM
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  6. Tyler Hallett

    Tyler Hallett New Member

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    Well now it is reading evaporation emissions system control valve: low/no flow.. I don't know what it is but I'm guessing it's fuel related. Maybe the gas cap or filter??
    #6

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