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Thread: O2-sensor defective?

  1. #1
    Dag
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    Aug 2016
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    Norway, Europe
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    O2-sensor defective?

    I did a live readout with HFM-scan in my 1993 500E.
    When the engine is idling or Iím driving and depress the accelerator, the
    appears:

    50% O2S 1 (before TWC) (G3/2) not operational or defective, open circuit

    The O2-sensor was swapped one year ago with an OEM part.

    Why does this only appear when the engine is idling?
    Is the sensor really faulty?

  2. #2
    .036 Hooniganô
    E500E Boffin
    gsxr's Avatar
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    Re: O2-sensor defective?

    If there are no stored fault codes, it may be a glitch with HFM Scan software. I'd compare to live data from a scanner designed for LH (SDS, MT2500, etc).

    Dave M.
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  3. #3
    Intl 500E GTG coordinator 195910's Avatar
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    Re: O2-sensor defective?

    Quote Originally Posted by little_e View Post
    I did a live readout with HFM-scan in my 1993 500E.
    When the engine is idling or I’m driving and depress the accelerator, the
    appears:

    50% O2S 1 (before TWC) (G3/2) not operational or defective, open circuit

    The O2-sensor was swapped one year ago with an OEM part.

    Why does this only appear when the engine is idling?
    Is the sensor really faulty?
    The live reading must constantly fluctuate around the 50% mark (48-52%) and not just read 50%

  4. The Following 2 Users Say Thank You to 195910 For This Useful Post:

    gsxr (3 Weeks Ago), TerryA (3 Weeks Ago)

  5. #4
    Dag
    Join Date
    Aug 2016
    Location
    Norway, Europe
    Posts
    52

    Re: O2-sensor defective?

    As I said, this fault ONLY appears when the engine is idling - if that is of any help.

  6. #5
    500E Terminus Illuminatus DerFuror's Avatar
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    Mar 2010
    Location
    USA
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    1,455

    Re: O2-sensor defective?

    Quote Originally Posted by little_e View Post
    I did a live readout with HFM-scan in my 1993 500E.
    When the engine is idling or Iím driving and depress the accelerator, the
    appears:

    50% O2S 1 (before TWC) (G3/2) not operational or defective, open circuit

    The O2-sensor was swapped one year ago with an OEM part.

    Why does this only appear when the engine is idling?
    Is the sensor really faulty?
    Double-check that the sensor connector is firmly & securely connected. A loose connection can cause the open circuit condition.
    " Destination ???, It's the ride that takes you there! "
    1993 500E W124.036 040/271
    1965 220b W111.010 Heckflosse

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