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2003 Ford Explorer Smog test failure

Tiny
ROBHUGHES19
  • MEMBER
  • 2003 FORD EXPLORER
Computer problem
2003 Ford Explorer 6 cyl Two Wheel Drive Automatic 108k miles

Fault codes PO 171&174 [system too lean - banks 1&2] were detected. Fix[s]? Costs? Thanks guys - aprreciated. Rob
Monday, February 23rd, 2009 AT 4:27 PM

1 Reply

Tiny
RASMATAZ
  • 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)
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Monday, February 23rd, 2009 AT 6:00 PM

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