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95 850 O2 issue 850

posted by  Quinn388 on  Wed Oct 21 03:44 CST 2009
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last visit: Fri May 4 12:06 CST 2012
[RELATED]

Afternoon. Just wondering if anyone else has had this problem. Replaced the front O2 sensor about a year ago, threw out the 153 and 212 codes (front and rear o2 faulty). Reset the light and it happened 3 more times and then never came on again.
Now I replced the rear sensor yesterday, just got the same 2 codes after about 60 miles. Does the computer take a little time to adjust to the new sensors?
Any ideas? Thank you.
Also, I've replaced about every sensor on the car, still only getting about 15 MPG.
quinn388.








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    95 850 O2 issue 850

    posted by  greendread on  Thu Oct 22 09:52 CST 2009
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    last visit: Tue Sep 2 08:56 CST 2014
    [RELATED]

    Hey I'm going through the same thing with my 96 855....

    Purge Valve to the Canister was bad $131 from the dealer... I took off and its running rich as hell! Good luck! let us know how it goes.

    cheers,

    greendread








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      95 850 O2 issue 850

      posted by  Quinn388 on  Sat Oct 24 03:38 CST 2009
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      last visit: Fri May 4 12:06 CST 2012
      [RELATED]

      Thanks, but I've already replaced the purge valve about a year ago. I've replaced just about every sensor and vacuum hose with the exception of the Cam Shaft Sensor, and the Crank Sensor. Still only getting about 15 MPG average.








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    95 850 O2 issue 850

    posted by  Quinn388 on  Thu Oct 22 07:00 CST 2009
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    last visit: Fri May 4 12:06 CST 2012
    [RELATED]

    Ok, disconnected the battery for 15 min, the car seems to be running a lot better, but the check engine light came on again with the same codes. Front and rear O2 sensors.








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      95 850 O2 issue 850

      posted by  KlausC on  Thu Oct 22 07:36 CST 2009
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      last visit: Fri Oct 24 10:15 CST 2014
      [RELATED]

      Sounds like your new rear O2 sensor is deffective.

      Klaus
      --
      Proud owner of a 1967 220S. If I had more room, I would have more Volvos.








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    95 850 O2 issue 850

    posted by  KlausC on  Wed Oct 21 05:23 CST 2009
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    last visit: Fri Oct 24 10:15 CST 2014
    [RELATED]

    The codes for sensor malfunction are usually caused by unmetered air getting into the intake manifold. This causes a lean condition at the front O2 sensor and the ECU compensates by increasing the fuel injector opening. Your MPG then goes downhill, the O2 sensor gets covered in soot and then fails again.

    Soooo, you probably have a vacuum line leak, a leaky vacuum tree, air intake before the throttle body leak, and/or a leaky intake manifold gasket. You could also have a broken diaphram in the fuel pressure regulator, allowing fuel to be flowing down the vacuum line to the tree and into the manifold.

    Take your pick from the above, and don't forget to clean up the PCV.

    Klaus

    --
    Proud owner of a 1967 220S. If I had more room, I would have more Volvos.








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      95 850 O2 issue 850

      posted by  Quinn388 on  Wed Oct 21 07:43 CST 2009
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      last visit: Fri May 4 12:06 CST 2012
      [RELATED]

      Thanks Klaus, but I've already replaced the (about 12 months ago) the Flame trap which required all new vacuum tubes and elbows and a new intake gasket, also replaced the fuel regulator at that time, Vacuum tree is fine, all hoses are Samco as well. Was running fine, I replaced the rear O2 to try to up the mileage, that's when the problem started. Also seems to bog a little when taking off.







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