Disco 2 V8 o2 sensor faults

Discussion in 'Discovery' started by Adrian Wilton, Mar 25, 2018.

  1. Adrian Wilton

    Adrian Wilton Member

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    guys, sorry if the answer to this has been posted, I Have. Disco 2 v8 with 4 x O2 sensors. I have bank 2 sensor 1 reading 0v?
    On idle is have a voltage then I drive and the voltage goes to zero? Maf changes, plugs and leads changed, o2 sensor changed.

    I can't find any split pipes, but I assume that as it's only one side I have either not enough fuel being burnt or an air leak? Also assume that the O2 readings are going out if limits hence goes to zero?

    Anyone had this before?
    Can I delete the O2 sensors and set the fuel?

    I would rather fix then hide the MIL light!

    Shame as car only has 48k on the clock and good condition other than this gremlin.
     
  2. joey

    joey Custom Rover Accessories Staff Member

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    If I were to gamble I would look for a cracked exhaust manifold.
     
  3. Adrian Wilton

    Adrian Wilton Member

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    Ok thanks,

    nothing obvious, but will take a better look tomorrow.

    Anything I can spray on it to help locate a crack?
     
  4. joey

    joey Custom Rover Accessories Staff Member

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    Generally you will see black around the crack. Or you can feel for the leak, just be careful not to burn yourself.
     
  5. Adrian Wilton

    Adrian Wilton Member

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    Cant see any issues with the manifold, any way of testing the valley gasket as a potential issue ?
     
  6. joey

    joey Custom Rover Accessories Staff Member

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    I would try carb cleaner while the engine is running and listen for the RPM's to change.
     
  7. swishewk

    swishewk New Member

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    If you can’t find any manifold leaks, check the fuel injector seals. When you pull off the fuel rail it should take some force to pull the injectors out. If they come out easily, replace the seals bill
     
  8. Adrian Wilton

    Adrian Wilton Member

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    Hi, thanks for the injector tip i will try this weekend, sorry for the delay in responding as have been working away.
    This fault is bugging me as the car drives on otherwise, though Fuel consumption gone up as i have one side closed loop and the other open loop.
    I have even looked at something to bypass the sensors...

    Will let you know what i find,
     
  9. joey

    joey Custom Rover Accessories Staff Member

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    Just remember if you drive it with this issue too long you will destroy the CATS.
     
  10. Adrian Wilton

    Adrian Wilton Member

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    Ok thought i would give a final update on this... it s sorted.

    I had replaced the O2 sensor indicated by the ECU, and this worked for about 20 miles and then the light came on again, lost readings to both sensors, so i replaced the second sensor after the CAT and also noted some oil in the harness, contact cleaner and it was sorted, or so i thought. Drove another 20 miles and the light came on again... same fault.

    So in desperation i replaced the pre CAT sensor again and the fault has now gone!

    The answer... Im not sure - Oil in harness maybe damaging a sensor ? who knows anyone posted this in case anyone else gets the same problems. 100 miles not and all still clear.
     

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