Code P0171, Permanent System too Lean Bank 1?

Tiny
ASHOK SAINI
  • MEMBER
  • 2013 BMW X3
  • 2.0L
  • 4 CYL
  • 4WD
  • AUTOMATIC
  • 175,000 MILES
I have smoke tested everything all tight, changed fuel cap, cleaned MAF and other sensor at throttle, installed new diverter valve, which have eliminated other faults but I keep getting this code even after I erase the temp code 118001 mixture control: Fuel-air mix too lean after driving 10-15 kms but this permanent code stays, I think is there anything /part under the engine valve cover which could be causing it but do not know what part is causing.
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Friday, November 17th, 2023 AT 5:42 PM

14 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,114 POSTS
Hi,

A lean fuel mixture can be the result of several things. First, I'm not familiar with the codes that are no longer present, so let me know what they were.

Next, things that can cause a lean mixture include but are not limited to, low fuel pressure, an exhaust leak before the up or downstream oxygen sensors, dirty fuel injectors, and the list goes on.

If your scan tool has a live data setting, check to see what the short-term fuel trims are first and let me know what they are. Also, watch the voltages at each of the oxygen sensors. They should be changing, but they should be within 0.1 and 1.0v.

I attached the description below of the code from my manual. Read through it and let me know if the things mentioned under the "Action in Service" section were related to the prior repairs.

Let me know.

Joe

See pics below.
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Friday, November 17th, 2023 AT 10:06 PM
Tiny
ASHOK SAINI
  • MEMBER
  • 32 POSTS
Thanks, Joe, for your reply. Can I upload a video of data stream for better clarification of the system issues. I am having?
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Friday, November 24th, 2023 AT 3:06 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,114 POSTS
Hi,

Absolutely, you can. I'll watch for it.

Joe
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Friday, November 24th, 2023 AT 7:12 PM
Tiny
ASHOK SAINI
  • MEMBER
  • 32 POSTS
Hi Joe,

I had attached video of data stream, as per your previous reply on Nov 24, please revert back if you got a chance to see the video.
Thanks,
Ash
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Monday, December 4th, 2023 AT 8:08 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,114 POSTS
Hi Ash, I never got a video. When was it sent?

Joe
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Monday, December 4th, 2023 AT 7:52 PM
Tiny
ASHOK SAINI
  • MEMBER
  • 32 POSTS
I uploaded in the reply section.
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Monday, December 4th, 2023 AT 10:15 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,114 POSTS
Hi,

I just went back through all of our posts and I'm not seeing anything. There is a picture of the code, but no video. Where did you put it?

Joe
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Tuesday, December 5th, 2023 AT 5:56 PM
Tiny
ASHOK SAINI
  • MEMBER
  • 32 POSTS
Attached 3 videos one full data stream of all functions, the 2nd one at approximately 700RPMs and last one at approximately 1,500 RPMs.
The lean code comes after 40-50 kms on 2nd start. I'm also using Lucas fuel system cleaner with 91 octane gas (BMW recommended) otherwise it runs great. Thanks for your help. I replaced the used engine last year it's 2015 versus 2013 before.
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Tuesday, December 5th, 2023 AT 6:48 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,114 POSTS
Hi,

I feel like a pain, but I don't see any videos.

Joe
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Wednesday, December 6th, 2023 AT 7:31 PM
Tiny
ASHOK SAINI
  • MEMBER
  • 32 POSTS
Any other way I can send you the data stream video?
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Friday, December 8th, 2023 AT 3:40 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,114 POSTS
Hi,

You can attach videos and images to this thread. There should be a tab at the bottom of your message that indicates, "Add image or video."

Let me know. Also, let me know if that is what you have already done.

Joe
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Friday, December 8th, 2023 AT 9:54 PM
Tiny
ASHOK SAINI
  • MEMBER
  • 32 POSTS
Yes, this is what I did 3 videos uploaded.
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Friday, December 8th, 2023 AT 11:03 PM
Tiny
ASHOK SAINI
  • MEMBER
  • 32 POSTS
Sending again. Different RPM data stream.
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Friday, December 8th, 2023 AT 11:07 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,114 POSTS
Hi,

I watched the videos. Am I correct in saying the short-term trims at times stay constant at 99%? Interestingly, the O2 sensor voltage was within spec and changing while that was happening. I have a question. In video one, the trims look okay. Then you press a button, I hear a beep, and the trims are stuck at 99.2%. What are you changing that causes that?

Joe
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Saturday, December 9th, 2023 AT 10:24 PM

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