LEAN CODE P0171/P0174

MYSWEETX5

MEMBER
2001 BMW X5
V8
AWD
AUTOMATIC
112,086 MILES

Everyone knows that there's alot to check with when it comes to these two lean codes: (P0171/P0174). But some vehicle may have very specific location as usual for this particular issue. And I wonder if anyone ever experienced this lean problem on the same car mentioned above, how do they resolved it. And how do I test the air mass sensor to see if it's working properly after cleaning it.

4 Replies

DOCHAGERTY

MECHANIC
9,601 POSTS

Hello,

When you have a lean code 9 times out of 10 it is the MAF sensor. Here are two guides and a video on how to change the MAF and other things to heck for the lean condition.

https://www.2carpros.com/articles/repair-lean-mixture-codes-p0171-or-p0174-on-some-manufacturers

and

https://www.2carpros.com/articles/how-to-replace-a-mass-air-flow-sensor-maf

Cleaning the MAF doesn't really work when the sensor is to far gone.

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Thursday, August 26th, 2010 AT 7:11 PM

JERRYGEARLD

MEMBER
0 POST

Thanks for this post I got a new MAF sensor for $97.00 and the problem is gone! I love this site.

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Tuesday, January 15th, 2019 AT 7:14 PM

MYSWEETX5

MEMBER
16 POSTS
2001 BMW X5
V8
4WD
AUTOMATIC
112,322 MILES

When I scanned my the vehicle with my computer, those code appear p0171/p0174 lean codes but when I checked further, the computer mentioned: (heater catalyst not ready, (egr valve not supported) (a/c refrigeration not supported)

what is that mean because I have 4 new 02 sensors.

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Tuesday, January 15th, 2019 AT 7:14 PM (Merged)

RASMATAZ

MECHANIC
75,992 POSTS

Lean fuel condition could be caused by one of the following below:

1. Vacuum leaks
2. EGR and PCV valve.
3. Low fuel pressure.
4. Dirty fuel injectors.
5. Mass Air Flow Sensor.
6. Oxygen Sensor.

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Tuesday, January 15th, 2019 AT 7:14 PM (Merged)