System Lean Bank 1 and 2 Codes?

KEIKERMAN

MEMBER
2001 FORD F-150
V8
4WD
AUTOMATIC
105,000 MILES

The service engine soon light lit on my 2001 f-150 w/5.4 V8. I checked the code and it came up as a P0171 and P0174 (System Lean Bank 1 and 2 respectively). It also appears the when it warms up the RPMs tend to fluctuate. Thought it might be because the injectors need to be cleaned so I put a fuel additive in to get rid of any build up in the injectors and it appeared to improve the problem. The RPMs still fluctuate but not as bad. The truck does have a K&N Filter and Intake on it and have heard that sometimes it could cause the mass air flow sensor to get dirty and that this could be a cause of the problem. Is this possible, and could it be as simple as cleaning the Mass Air Flow Sensor?

Saturday, December 29th, 2007 AT 12:59 AM

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
54,141 POSTS

Yes, you are on the right path, the MAF sensor is the #1 cause of this kind of problem, and you are right the KN filter will cause the MAF sensor to get dirty prematurely. Here are instructions in the images below on how to change it out to help fix the problem.

https://youtu.be/ueHWUF6F120?si=81hQki1BgtB8FyP0

The sensor is inside the air filter housing. Check out the images (below). Let us know if you need anything else.

Images (Click to make bigger)