Code P0171, Permanent System too Lean Bank 1?

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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4 Replies

JACOBANDNICKOLAS

CERTIFIED MECHANIC
106,595 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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