N63 lean mixture

imageHere’s a picture of good old smokey,,,,I have a   N63TU 2014 650 with the check engine light on,,,,,check faults memory,,,,,found 2 faults  both on bank 2,,,,,lean mixture bank 2,,,,,and O2 sensor after catalytic converter lean mixture slow to respond ,,,,performed test plan for lean mixture and it said problem is the O2 sensor,,,,but me knowing better the O2 sensor could be one of the problems,,,,,but there could be another problem causing the problem,,,,,so to be sure,,,,I decided to smoke test the intake system on bank 2,,,,and look what I found a intake leak,,,,the plastic intake running that goes into the turbo is leaking pretty bad,,,,,,they do leak a little because it’s not a great set up and never seals 100%,,,,,but it shouldn’t be this bad.image Here what I found once I removed the plastic intake running to the turbo,,,,,,notice how the plastic ear tab is cracked,,,,,,and that one eye hole is where it gets mounted on,,,,,so that whole intake running was loose and causing the intake leak.image Here is the old one and the new one,,,,the new one is the one with the orange turbo seal at the end,,,,,that’s also one of the new seals we replace during the customer care package.

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18 Responses to N63 lean mixture

  1. simon says:

    Hi, I had the same problem on my 650ix from 2011. It is woth to check this part sometimes,,,


    • Yes you can check it out,,,,,they might have already updated it with the new orange seal during the customer care package,,,,,do you still have the lean mixture fault? Or was to fixed?,,,,because there are many possible problem that can cause a lean mixture fault


      • simon says:


        as I from Germany we do not have the ccp. My workshop found it because I had a burned oil smell in the car. The reason was the same crack. Some oil (from the charger air) was leaking and was burned on the engine surface.

        BR Simon


      • That’s interesting you don’t have the cap in Germany ,,,,,what part of Germany are you from,,,,,I was just there last year.


  2. a.a. says:

    Wow. That’s fantastic information and something where experience goes a long way…
    Had you not found the crack and replaced the O2 sensor only, is there a possibility that running the test again would have reported it “fixed”?


  3. simon says:

    @bmwtechnician: I am located in Munich / Bavaria (but actually sitting in Thailand for Vacation…)


  4. Thanks for this, I am about to go and check this pipe as I swapped over Bank A to B and fault remained the same. Do you know if this kind of fault would make the car a little more difficult to start ? Thanks in advance! 🙂


  5. Kris says:


    Amazing blog! How can we donate?
    I just noticed that my tubes have black seals and it seems there is some play in pipes ( no cracks I inspected with boroscope )

    Car is 2013 so no CCP for it as far as I know?

    Please see picture and tell me if this play is ok or that scree should be tighter

    There some dirt and oil mist around both pipes not sure if that’s normal.

    Since I have no codes, do I need to address the seals asap? Is play on pipe normal… It feels like it’s not a tight seal.

    Thank you


  6. Maxx says:


    I got code for P0141 – Sensor Heater Circuit Bank 1 Sensor 2.

    2013 – N63 TU, since no lean condition… I’m thinking about getting new sensor. ( 35k miles on the car )

    What you think?

    Where did you introduce smoke for the test? Via filter or MAF hole ?

    Thanks for amazing blog !


  7. Bob says:


    Hope you are staying well and healthy!
    Is replacements of those seals a big job or it’s accessible without removing anything ?



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