Error code P0174 + P0171 since smoke from exhaust at cold start

  • Hi there.

    I've been reading along in the background for a very long time. About 1 year ago I finally fulfilled my dream of having my own 11 in the form of a 996 4s.

    Since then I've done a lot of work on wear parts and the look of the vehicle. I'm actually very satisfied now. Now the MKL came on recently while driving relaxed. Error read out P0174 and P0171 exhaust lean. On both benches. So I checked a bit and thought I'd put in a new LMM first. Who knows how old it is and it's quick to do. Bosch part purchased and installed. Error deleted. The light has also stayed off until now. But since then it smokes from both exhaust silencers at cold start.

    For a few seconds. Definitely never was before. I think the engine sounds at idle as if the engine is drawing secondary air. But I haven't found anything about it.

    Now I've read around a lot and am wondering whether the whole thing is possibly connected to the oil separator. What do you think? Could it be the oil separator?

    I've read a lot about replacing it without removing the engine. But mostly with the switch. I have a Tiptronic. Is that also possible?


    I also rarely have a small puddle of coolant at the rear left and a slight coolant odor.


    Is there a coolant connection on the oil separator?


    I look forward to your opinions and tips.


    Greetings from Hamburg.


    Machinist


    Here is another picture of my 11...


    Addendum: the smoke has been there since the MKL came on. Not since the LMM was changed

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  • Hi Maschi


    From a distance, it sounds as if the one has nothing to do with the other, it sounds like the oil separator is really working.


    :pfeil: However, a little smoke is "normal", especially after short journeys and then not moving for several days. This is the "boxer fart".


    :pfeil: Check two things before you start the removal: 1. is there any cooling water missing? 2. check the oil level with the oil dipstick, possibly overfilled? I'm not aware of any difference between the switch and Tiptronic when removing the oil separator, I've never read anything about it. There is no cooling water in the oil separator, you can simply remove it. It may be full of oil residue, in which case it drips a little. It can also drip into the mechanic's face... k:acute:

    The main problem is a nut at the rear left of the intake manifold, which you have to unscrew without being able to see it and then screw it back on again later. If you do it yourself, get yourself a screw clamp so that you don't have to spend hours choking the clamp back on, or alternatively a pair of pliers to open the clamp.


    :pfeil: If the separator is defective, there is no error message, so you should read out the errors with the MKL again (or have them read out). There seems to be something wrong.


    Greetings

    tkm

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  • I also rarely have a small puddle of coolant in the left rear and a slight coolant smell.

    The left rear is of course relatively ................

    Have a look at the lid of the coolant tank and the tank for traces, the lid is often cracked - that was also the case with me; there was always a little coolant under the car; replaced the lid, problem solved.

    The reservoir also cracks very easily and then leaks - but then it wouldn't be occasional; but of course it also depends on the size.

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    Boxster 986...verkauft
    996 Coupe...verkauft
    996 tt cabrio wls...und noch ein paar PS mehr draufgepackt

  • Hello Tkm,


    Many thanks for your answers.


    I've often read about the boxer fart. But I definitely never had that. Driving style has not changed.


    I have read out the error, there is nothing in it.


    I deleted the error with the old LMM, but it came back after about 20 minutes of driving.

    Nothing with the new one so far. So I assumed that the error was gone. But this smoking puzzles me. Because as I said, it was definitely never there before.

    🤷🏻‍♂️

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  • I also rarely have a small puddle of coolant in the left rear and a slight coolant smell.

    The left rear is of course relatively ................

    Have a look at the lid of the coolant tank and the tank for traces, the lid is often cracked - that was also the case with me; there was always a little coolant under the car; replaced the lid, problem solved.

    The tank also cracks very easily and then leaks - but then it wouldn't be occasional; but of course it also depends on the size.

    The tank has already been replaced by the previous owner. I don't think the lid did. The strange thing is that it is absolutely irregular. I had a small puddle 2-3 times near the left rear tire. Always after a short drive and then parking. And then nothing again for a long time. I have already pressed the system but nothing came out.

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  • Had a small puddle 2-3 times near the left rear tire. Always after a short drive and then parking. And then nothing again for a while.


    It was exactly the same with me; no traces or anything similar on the cover. I was pretty clueless at the time, but the water had to come from somewhere - so I bought a new cover - it didn't cost a fortune - and that was that.


    I pressed the system once but nothing came out.


    Then you can normally assume that the tank itself is tight.

    But you should have been able to see something around the oil separator if it was the culprit.

    This post has been automatically translated.

    Boxster 986...verkauft
    996 Coupe...verkauft
    996 tt cabrio wls...und noch ein paar PS mehr draufgepackt

  • Well, if the oil separator doesn't have a connection for cooling water anyway, it's ruled out for the problem anyway.


    I'll just order a cover then. 👍🏼

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