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Mk1 Focus failed NCT on emissions (low and high idle). Any ideas what it might be?

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  • 23-10-2023 12:28pm
    #1
    greengravel
    Registered Users Posts: 13 ✭


    At the mercy of cowboy mechanics and looking for opinions before I spending anything on it.

    IMG_0750.png




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    #2
    kdevitt
    Registered Users Posts: 2,254 ✭✭✭kdevitt


    https://www.boards.ie/discussion/2058319277/mk1-focus-failed-nct-on-emissions-low-and-high-idle-any-ideas-what-it-might-be

    Potentially an o2 sensor - lambda is low, which is impacting the fuel mixture.



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    #3
    Irish_wolf
    Registered Users Posts: 261 ✭✭Irish_wolf


    Have you tried Dipthane? Used to have a mk1, great car but needed a good dose of dipthane to pass the emission tests. As above your O2/lambda sensor could be gone, that's a common issue on the mk1, you can do some backyard maintenance on it by taking out the sensor and dipping it in strong vinegar for a day or so and then wash off any scale or soot. Hard sensor to get at if you dont have a car lift mind you.



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    #4
    JP 1800
    Registered Users Posts: 322 ✭✭JP 1800


    That is running vey rich, so its overfuelling. High CO would indicate it is burning through more fuel than normal also the higher HC would indicate not all the fuel is being burned off during the combustion cycle. I would do a full service including new oil and filter, air filter including new spark plugs. Also as mentioned replacing the O2 sensor may be required. Are you experiencing a misfire by any chance?, higher HC readings can indicate misfires. From memory the spark plug boots on those engines can allow water to collect in the spark plug channels and cause misfires.



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