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Help - Failing NCT on Emissions

  • 11-10-2012 9:12am
    #1
    Trackerc
    Registered Users, Registered Users 2 Posts: 3 ✭


    I've a 2002 Volkswagen Passat 1.6L Petrol which is failing the NCT on emissions, specifically we have a .27 reading on CO2 at high idle and it should be below .2.

    I have recently got an O2 sensor replaced from front of CAT which turned off a long running engine management light but did nothing for the emissions.

    I have done all that I can in terms of having the engine hot before test, using Dipthene etc. but .27 is best reading and everything else is fine.

    The CAT has been replaced on this car previously so do not want to go down that road. Does anyone else have any other suggestions?

    Thanks for your help


Comments

  • #2
    George Dalton
    Registered Users, Registered Users 2 Posts: 5,728 ✭✭✭George Dalton


    When the cat was previously replaced what type of replacement was fitted?

    New genuine?
    New aftermarket?
    Secondhand?

    How long since the replacement cat was fitted?


  • #3
    Trackerc
    Registered Users, Registered Users 2 Posts: 3 ✭Trackerc


    As far as I know, it was a new generic cat, not a Volkswagen part. It was about 2 to 3 years ago.

    Thanks


  • #4
    George Dalton
    Registered Users, Registered Users 2 Posts: 5,728 ✭✭✭George Dalton


    Well if it is a generic cat and it is 2-3 years old then it most likely needs to be replaced again IMO.


  • #5
    AzureAuto
    Banned (with Prison Access) Posts: 233 ✭✭AzureAuto


    I agree with George. Assuming that the engine is in good condition, i.e. air intake clear and filter not blocked and injectors performing well and long term fuel trim values when read on diagnostics not over 3% (i.e. indicating that ECU is over compensating for a fault in the fueling/emissions control system) then the CAT is most likely the problem. That said though, spurious O2 sensors are sometimes not up to scratch like the OE Bosch ones....A decent mechanic will be able to check these things over for you before you hand over money on potentially expensive parts


  • #6
    PADRAIC.M
    Registered Users, Registered Users 2 Posts: 2,189 ✭✭✭PADRAIC.M


    With Co failing like that I would change front o2 sensor first,


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  • #7
    Sunflower73
    Registered Users, Registered Users 2 Posts: 3 ✭Sunflower73


    Hi, my 2004 ford focus has failed nct on emissions:
    Low idle co 1.76 vol% should not be above .50%
    High idle co .93 vol% should not be above .30%

    I had a generic catalytic converter but in about 7 months ago and also new sensors. Garage has said I need a new cat as they don't last, I know it was a generic one but would have thought it would last a bit longer than that, the garage I had it fitted in has since closed down

    Any advice would be greatly appreciated


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