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My orange light came on today.

PO171: Bank 1 lean.

Any ideas on what may fix this. I cleared the code, and it hasen't came back yet, but I still want to get it taken care of.
 

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chocolatekoolade said:
My orange light came on today.

PO171: Bank 1 lean.

Any ideas on what may fix this. I cleared the code, and it hasen't came back yet, but I still want to get it taken care of.
I went through my Ford Manual on CD. I'm just copy/pasting, so you'll have to read through it all...

P0171 System (adaptive fuel) too lean (Bank #1)


Diagnostic Trouble Codes (DTCs) P0171 bank (1) (cylinder #1) and DTC P0174 bank (2) indicate the fuel/air ratio is too lean. The fuel adaptive system is at the rich correction limit.

DTC P0172 bank (1) and DTC P0175 bank (2) indicate the fuel/air ratio is too rich. The fuel adaptive system is at the lean correction limit.

DTCs HO2S Reference list:

-- HO2S-11 = DTCs P0171 and P0172

-- HO2S-21 = DTCs P0174 and P0175

Possible causes:

Fuel system

-- Excessive fuel pressure.

-- Leaking fuel injector(s).

-- Leaking fuel pressure regulator.

-- Low fuel pressure.

-- Contaminated injector(s)

Induction system

-- Air leaks after the MAF.

-- Vacuum leaks.

-- Restricted air inlet.

-- PCV system.

-- Fuel purge system.

-- Improperly seated dip stick.

EGR

-- Leaking gasket.

-- Stuck open EGR valve.

-- Leaking diaphragm.

Base engine

-- Oil overfill.

-- Cam timing.

-- Cylinder compression.

-- Exhaust leaks before or near the HO2S's.

l Check air intake for leaks, obstructions and damage.

l Check air filter, air filter housing for blockage.

l Verify integrity of the PCV system.

l Check for vacuum leaks.
 

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i had exactly the same code and i checked all the possibilities mentioned above from my shop manual. it turned out to be a dirty maf (i'm not saying it's not one of those indicated above, just giving you another option)
 
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