F30 N26

Imperial328i · 07-06-2020, 12:52 AM

I started getting this code a few months back. I replaced the upstream O2 sensor and all seemed well. Tonight it came back. Tomorrow I'm going to try some CRC MAF cleaner. If that doesn't help, I'm going to make sure my intake tract is sealed well enough. Beyond that, we will see. Just wanted to make a thread to log my progress because I'm not finding good first hand accounts online with the N20/26. Anyone have experience with this? Thanks in advance

bmwchue · 07-06-2020, 02:18 AM

p0171 means system running lean so not enough fuel. could be anything related to fuel.

Imperial328i · 07-06-2020, 09:18 AM

Quote:

Originally Posted by bmwchue

p0171 means system running lean so not enough fuel. could be anything related to fuel.

Yep, but also likely air. Before I go tearing into injectors I'm going to look at air. Just cleaned the MAF this morning. About to test drive.

mmaczynski · 07-12-2020, 11:41 PM

I've been having this issue too. It showed up in the winter when temps started to drop- never got a chance to look at it and now that it got warmer the code disappeared but I still have no idea what the problem could be. Definitely keep this thread updated! I could use the info

Imperial328i · 07-13-2020, 07:21 PM

Sorry, forgot I made this thread. It's been a week or so since I cleaned the MAF. No trouble since! Time will tell. I'm doing a walnut blast on the intake valves this weekend, hoping this will smooth the idle out and free up some ponies as well.

pierreye · 07-14-2020, 06:00 AM

Please take some photo for your intake valves before and after walnut blast. Would be good to compare how dirty the valve is based on the driven mileage.

Imperial328i · 07-14-2020, 10:38 AM

Quote:

Originally Posted by pierreye

Please take some photo for your intake valves before and after walnut blast. Would be good to compare how dirty the valve is based on the driven mileage.

Oh yeah, I plan on lots of documentation. I'm gonna do a whole thread.

Senhorcheeks435 · 02-03-2022, 06:49 PM

My mechanic trouble shot mine … was the fuel pump … f36 fbo

mcotorres · 12-21-2023, 01:09 PM

can some advice on what to check before taking to mechanic. I get the same code on my bmw 335i sedan

M3_V8_PWR · 01-03-2024, 08:05 PM

Quote:

Originally Posted by mcotorres

can some advice on what to check before taking to mechanic. I get the same code on my bmw 335i sedan

Might be the fuel pump

deepsix · 01-31-2024, 09:37 AM

I just had the same code on my F31 2018 330i with the B46. The dealership diagnosed the issue was related to the fuel tank vent valve on top of the engine adjacent to the oil fill cap. A newer version of the same part was installed and the issue was resolved.

I found a youtube video showing the specific part in question.

07-06-2020, 12:52 AM	#1
Imperial328i Lieutenant 277 Rep 558 Posts Drives: 2015 MGM 328i, 2017 LBB M2 Join Date: Jan 2018 Location: Southern Maryland iTrader: (1)	F30 N26 - P0171 System too Lean Bank 1 I started getting this code a few months back. I replaced the upstream O2 sensor and all seemed well. Tonight it came back. Tomorrow I'm going to try some CRC MAF cleaner. If that doesn't help, I'm going to make sure my intake tract is sealed well enough. Beyond that, we will see. Just wanted to make a thread to log my progress because I'm not finding good first hand accounts online with the N20/26. Anyone have experience with this? Thanks in advance __________________ 2017 F80 ZCP - Mineral Grey Metallic
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07-06-2020, 02:18 AM	#2
bmwchue Captain 242 Rep 804 Posts Drives: 2013 bmw 328i Join Date: Oct 2017 Location: California iTrader: (0)	p0171 means system running lean so not enough fuel. could be anything related to fuel.
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07-12-2020, 11:41 PM	#4
mmaczynski New Member 2 Rep 5 Posts Drives: 2013 BMW 328i Join Date: Apr 2019 Location: Chicago iTrader: (0)	I've been having this issue too. It showed up in the winter when temps started to drop- never got a chance to look at it and now that it got warmer the code disappeared but I still have no idea what the problem could be. Definitely keep this thread updated! I could use the info
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07-13-2020, 07:21 PM	#5
Imperial328i Lieutenant 277 Rep 558 Posts Drives: 2015 MGM 328i, 2017 LBB M2 Join Date: Jan 2018 Location: Southern Maryland iTrader: (1)	Sorry, forgot I made this thread. It's been a week or so since I cleaned the MAF. No trouble since! Time will tell. I'm doing a walnut blast on the intake valves this weekend, hoping this will smooth the idle out and free up some ponies as well. __________________ 2017 F80 ZCP - Mineral Grey Metallic
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07-14-2020, 06:00 AM	#6
pierreye Lieutenant 212 Rep 500 Posts Drives: F10 & G01 Join Date: Jun 2018 Location: Malaysia iTrader: (0)	Please take some photo for your intake valves before and after walnut blast. Would be good to compare how dirty the valve is based on the driven mileage.
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02-03-2022, 06:49 PM	#8
Senhorcheeks435 Enlisted Member 0 Rep 31 Posts Drives: Bmw 435 GC Join Date: Mar 2020 Location: Toronto iTrader: (0) Garage List 2015 Bmw 435 [0.00]	Same prob but got it fixed My mechanic trouble shot mine … was the fuel pump … f36 fbo
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12-21-2023, 01:09 PM	#9
mcotorres Registered 0 Rep 1 Posts Drives: 335i Sedan 2015 Join Date: Dec 2023 Location: NY iTrader: (0)	can some advice on what to check before taking to mechanic. I get the same code on my bmw 335i sedan
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01-31-2024, 09:37 AM	#11
deepsix Registered 3 Rep 4 Posts Drives: 2018 F31 330i, 2011 E82 128i Join Date: Jun 2023 Location: Canada iTrader: (0)	I just had the same code on my F31 2018 330i with the B46. The dealership diagnosed the issue was related to the fuel tank vent valve on top of the engine adjacent to the oil fill cap. A newer version of the same part was installed and the issue was resolved. I found a youtube video showing the specific part in question.
	Appreciate 0 Quote