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Black smoke

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  • Black smoke

    Hi, just looking for some advice. A few months ago I noticed some black smoke from the exhaust on my 155 THP. It spectacularly failed its MOT on emissions the week after this. The O2 sensor was changed and following this it passed the MOT absolutely fine.

    Now, I noticed black smoke again a few weeks back and replaced the O2 sensor again. This worked for a few weeks, and now the black smoke is back!

    What on earth is destroying my O2 sensors?

    Any ideas?

    DS3 THP 155 - stage 2+ remap, milltek sports cat and non resonated exhaust system, airtec FM intercooler and alloy boost pipes, induction kit. Mtech short shifter, VAG recirculation valve with uprated alta spring, uprated hpfp, uprated spark plugs, uprated coil pack, VTA twin pcv to filtered catch can, uprated Sachs clutch, ebc brake pads and vented discs, LED interior lighting, rcz gearknob, Michelin pilot sport 4s, iridium spark plugs

  • #2
    With all the mods detailed in your signature, would suggest that you probably have a better idea than us

    Fuel mixture? Cat Converter? Is the O2 sensor before or after the Cat?
    Looks like some sort of combustion problem

    maybe run a fuel system cleaner through?
    Jog on Noddy