Question about 2002 Ford Explorer
Check your work for vacuum leaks,can't have any
Replace the front oxygen sensors, if they have 100,000
miles on them That is the 171&174 along with vacuum leaks
& worn out slow sensors
PO203 ---is a #3 injector issue
Listen to hear if it ticks-- like the others & compare
OHM readings to the others
Posted on Nov 30, 2012
P174 FUEL SYSTEM TOO LEAN CYLINDER BANK 2 AND CODE P203 CYLINDER 3 INJECTOR CIRCUIT MALFUNCTION. POSSIBLE CAUSES COULD BE DAMAGE OR SHORT IN CONNECTOR OR PCM NOT FIRING FUEL INJECTOR.
Posted on Dec 01, 2012
P0203 is "injector circuit malfunction, cylinder 3", Did you remove the injector harness when you replaced the intake? Try unplugging and reconnecting the injector connector on cylinder 3. Does it still plug in good, no pins bent in the connector?
The other codes indicate "system too lean" on both banks (sides) of the engine, so if you get the injector working on cylinder 3, it should clear up the lean running condition.
Posted on Nov 30, 2012
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Posted on Jan 02, 2017
SOURCE: Code #P0171 & code #P0174
The intake manifold gaskets need replacement as well as the o-rings inside - if you call FORD they should be able to get you the correct parts.
Posted on Nov 05, 2008
SOURCE: check engine light codes, p0171,
this fords have very comun problems with maf sensors geting contaminated, if you have not or can hear any vacium leaks, the problem is goin to be a conataminated mas air flow snsor (maf)
allow the engine to cold down for at least 15minutes and the remove the air filter hosing and inside has to have a sensor, clean the two liitle resistors inside with brake or carburetor cleaner, allow it to dry and reinstall it.
if this inf help please mark it as fixya ranking after you try what i said
Posted on Jun 30, 2008
if you have the 3.8 liter its more than likely bad intake manifold gaskets or a cracked manifold. Ford has had several TSBs on this issue. O2 sensors do not go bad as often as mechanics say they do. I have a 1999 that after 100 dollars at the parts store solved all lean conditions on the top end. The manifold has three parts to it. A lower aluminum that houses the butterfly blades for the variable intake runners( known vacuum leak were rods protrude at passenger side of lower bad bushings likely cause). Middle riser which uses oring seals which dry out and cause major vacuum leaks. upper is more or less the top cover which uses one large oring to seal. Hope this helps!
Posted on Apr 18, 2009
Very common concern with the Explorer, Explorer Sport Trac and Ranger with the 4.0l SOHC engine! The upper and lower intake manifold gaskets fail, causing vacuum leaks..It can be Extremely difficult to detect these leaks, because they only leak intermittently (usually in the AM after a cold soak)... As the engine warms up they seal back up! Sometimes the vehicle will idle rough, surge or stall after initial start up, then the symptoms will clear after it gets to operating temperature... Usually there will be no driveability symptoms at all, except the engine light coming on and setting lean codes.. The gaskets have been redesigned to correct this concern..
Bill Andrade Ford Master Technician/ASE Master Technician
Posted on Sep 22, 2009
You could be right but before going to all that trouble of replacing the intake gasket take a close look at the MAF (Mass Air Flow) sensor. Also look for a vacuum leak downstream of the MAF sensor. The MAF sensor may be dirty especially if you are using an "oiled" air filter and it was over oiled. Remove the MAF sensor and clean it with electronic cleaner. Make sure it is dry before reinstalling. If it is damaged, replace it. Also replace the fuel filter as a partially clogged filter has been know to set this code on some vehicles. Check all vacuum hoses and replace as necessary.
Posted on Nov 14, 2009
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