1998 Ford Expedition Code PO171

1998 FORD EXPEDITION
222,000 MILES • V8 • 4WD • AUTOMATIC
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PKJFS
  • MEMBER
  • 5 POSTS
I started getting the PO171 Code showing up on my code reader. The only thing that was done was the fuel filter was replaced at PENZOIL location when my wife took the car in. I'm thinking they didn't de-pressurize the fuel system before changing the filter, am I wrong in my thinking?
Mar 28, 2009 at 1:55 PM
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RASMATAZ
  • ✓Experienced Mechanic
  • 75,992 POSTS
A lean fuel condition can be caused by:

* Low fuel pressure due to a weak pump or leaky fuel pressure regulator. (use a fuel pressure gauge to check fuel pressure at idle)

* Dirty fuel injectors. (try cleaning the injectors)

* Vacuum leaks at the intake manifold, vacuum hose connections or throttle body. (Use a vacuum gauge to check for low intake vacuum)

* Leaky EGR valve. (Check operation of EGR valve)

* Leaky PCV Valve or hose. (Check valve and hose connections)

* Dirty or defective Mass Airflow Sensor (MAF). (Try cleaning the MAF sensor wires or filament with aerosol electronics cleaner. Do NOT use anything else to clean the sensor, and do not touch the sensor wires)
Mar 28, 2009 at 11:25 PM
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