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Should I change the O2 sensor? V70-XC70 1998

posted by  jmargush on  Tue Mar 10 13:10 CST 2009
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last visit: Fri Sep 26 05:29 CST 2014
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1998 V70 170k miles I had a CEL code that called out slow response on the front O2 sensor. I replaced this with a universal sensor and the mileage dropped to 19mpg hwy.CEL keep throwing the same code. So I did some searching on the boards and did the cleaning procedure on my old sensor put it back in and had the code cleared. CEL hasn't come back on and mileage is a bit better but not back to 26mpg.

Should I put in a new specific sensor or if the CEL isn't coming on should I leave it?








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    Should I change the O2 sensor? V70-XC70 1998

    posted by  KlausC on  Tue Mar 10 17:09 CST 2009
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    Nothing like a good O2 sensor. The generic ones, you get what you pay for. It is also time to start looking for vacuum line leaks around the intake manifold.
    --
    My name is Klaus and I am a Volvoholic.








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      Should I change the O2 sensor? V70-XC70 1998

      posted by  jmargush on  Wed Mar 11 04:28 CST 2009
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      will those vaccuum leaks throw a code?








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        Should I change the O2 sensor? V70-XC70 1998

        posted by  KlausC on  Wed Mar 11 05:14 CST 2009
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        Not directly. A leak into the intake manifold will cause the ECU to increase fuel volume and then cause the exhaust to have more unburned fuel, which then causes the front O2 sensor to get dirty and less efficient. Then the code for the O2 sensor is set.
        There are ocassions where the heating element will not be efficient because of the dirt, allowing the heater to stay on too long and slowly burn out - that causes its own code, a slow responing O2 sensor.

        There are 2 critical maintenance items that get overlooked by mechanics, usually because they take so long to develop. Cracked vacuum lines and clogged PCV lines/oil separator box, neither of which have diagnostic codes.
        --
        My name is Klaus and I am a Volvoholic.







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