[Orion4]

Cant seem to find any DIY for this. I'm a 2013 F30 N55 at 143,000 and getting an fault code 118001, “Mixture Control: Mixture too lean". That is the only fault code I am getting. Neither I or my BMW Master Mech- now an Indy, can chase down the culprit. He's going to some research, but suspects it may be the upstream O2 sensor.
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[Logicoeur]

That's because it's the very same job as removing the downpipe.

[Polo08816]

Originally Posted by Logicoeur

That's because it's the very same job as removing the downpipe.

This.

[Orion4]

So I will have to remove the Down-pipe to get sufficient access to R&R the upstream O2 sensor? I was afraid of that! Ugh!

[thejeremyman9]

Originally Posted by Orion4

So I will have to remove the Down-pipe to get sufficient access to R&R the upstream O2 sensor? I was afraid of that! Ugh!

I would at least check from the top before going to pull the DP. I think it will depend on your DP and the location/orientation of the upstream O2 sensor hole. Some aftermarket DPs are different. I think its possible you might be able to get to it from the top.

[Orion4]

Took a look. Can easily see it , but don't think i can get that deep from the top to get enough purchase or rotational range to loosen or tighten.

This photo is rotated 45 degree clockwise from the correct position.

[thejeremyman9]

Originally Posted by Orion4

Took a look. Can easily see it , but don't think i can get that deep from the top to get enough purchase or rotational range to loosen or tighten.

This photo is rotated 45 degree clockwise from the correct position.

Hard to tell without a higher up photo but you would probably need a long open end wrench, or a crow's foot O2 sensor socket with a long handled socket driver. Its possible you might also be able to reach up from the bottom, without removing the DP. Depends on tools available to you. DP removal and reinstall isnt too bad, just make sure you have the bottom Vband at a minimum as it is not really reusable. You may also want the gasket, however, did i did mine, i did not need to replace the gasket at the turbo.

[Orion4]

Thanks for the feedback and suggests. Will take a look from the bottom as soon as I recover more from the meniscus surgery on the left main-mount!

[EnzoKhan]

Originally Posted by Orion4

Cant seem to find any DIY for this. I'm a 2013 F30 N55 at 143,000 and getting an fault code 118001, “Mixture Control: Mixture too lean". That is the only fault code I am getting. Neither I or my BMW Master Mech- now an Indy, can chase down the culprit. He's going to some research, but suspects it may be the upstream O2 sensor.
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Were you able to resolve this issue? Im going through something similar:

I was getting 2BCB (mixture control: exhaust gas after catalytic converter too lean) code along with 2D2F (oxygen sensor before cat: multiple fault). 2cF4 code showed up once but didnt return after clearing (before cat slow response). This prompted me to replace the primary O2 sensor.

After replacing the primary O2 sensor and driving for a bit these two codes came up:
2D34 ( oxygen sensor before catalytic converter, system check: signal fixed at rich.
2D2F (Oxygen sensor before cat multiple fault)

The car drives and pulls smooth. It idles smooth as well before and after replacing the sensor. No SES light illuminated yet. What can I do now to hopefully resolve this matter and ensure the engine isnt running too rich or lean?

Car info:

2011 e92, N55 with 126k miles. Catless downpipe with mhd stage 0 tune for the past year. Just regular oil changes. No other work was done recently.

If you can please shed some light on this matter, that'd be greatly appreciated, thank you!