2001 Ford Expedition Emissions

MP5912

MEMBER
2001 FORD EXPEDITION
V8
2WD
AUTOMATIC
106,345 MILES

The check engine light has come on saying that my expedition has a lean fuel mixture in banks 1 and 2.
I have replaced all oxy sensors and the light still comes on. Could you tell me what the next step might be to resolve this issue?

Wednesday, December 3rd, 2008 AT 3:59 AM

1 Reply

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)