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Po171 and po174 codes on a 2002 ford f-150 harley davidson 5.4l supercharged

Replaced vacuum line from the pcv valve. cleaned the maf sensor

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  • Tom Collins Feb 23, 2012

    used carb spray on all vacuum lines, around the upper and lower intake. reset the codes and it took almost 150 miles before it came back on.



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Posted on Jan 02, 2017

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SOURCE: po171 po172 po174 po175 ???

If the fuel pressure was low enough to give lean codes then u would have a loss of power that you would easily notice, you say you checked for vacuum leaks, did you use a can of carb spray or a bottle of propane? it only takes a very small leak to trigger the codes, spray carb spray around the intake area, see if the engine sound changes, this will indicate a leak,

Posted on Nov 11, 2008

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Check for engine vacuum leaks, use a can of carburetor spray and spray around the top of the engine, pay close attention to the intake manifold, if there is a leak the engine will speed up a little, also the MAF may be defective, cleaning it does not always fix the issue, which is the heated sensor wire no sending the correct signal. My knowledge base? Ford certified Master electronics technician.

Posted on Dec 12, 2008

  • 6674 Answers


Both appear to be a lean mixture problem according to my research. Have you run some injector cleaner through it by any chance? What about coolant level, is it staying up, pressure tested, just in case coolant is mixing with fuel via, head or intake gasket leak, and leaning out the mixture. Low fuel pressure will cause lean mixture in some cases, test it or at least change filter if not done recently, or both. Hope that helps.

Posted on Dec 12, 2008

  • 147 Answers

SOURCE: codes 171 and 174 2001 ford winstar

dont take soo much in consideration after you have make all this things, some time is on only for any wire faulty, or a shrt electrical arc in any place in wire system. ask auto tap mechsnics for this maybe they have similar case before.

Posted on Apr 06, 2009

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1 Answer

2003 Ford Expedition check engine light on .Codes PO171 & PO174

This is a tough one could be mass air flow sensor ,oxyegen sensors,a fuel filter. a vacum leak, a pcv valve if i missed anything just google po 171 &174 look for fix ya this issue has been addressed many times first check the vacum lines includeing the line on the pcv valve for cracks or splits in the lines .I would do the fuel filter if it hasnt been changed in the last couple of years , if still a problem the MAF sensor if your happy with my advise please leave me with great feedback

Feb 18, 2013 | 2003 Ford Expedition

1 Answer

My engine idles and runs fine but has codes po171 and po174

Your still lean on both banks

Either the oxygen sensors failed or slowed
down & set a code or you have vacuum leaks

When ever you remove an intake-- you smoke it before
& after the job-- to avoid vacuum issues

Fuel Trim may give you some idea where to start

Can be rich both banks & driven lean

Dec 17, 2012 | 2002 Ford F150 Regular Cab

1 Answer

2007 Ford Expedition 5.4L revving while driving normally after sitting idle...sometimes will give a **** after revving. Check enging light just came on. Autozone said code PO171 & PO174. Fuel filter...

Replace the spark plugs & only install the one piece
Champions 7989

Replace the front or upstream Oxygen Sensors at 100,000 miles

Clean the MAF Sensor--CRC MAF Cleaner (instructions on can)

The 171 & 174 are lean condition both banks,your doing the
sensors based on mileage & the fact their about to fail or slow
down anyway (Preventative Maintenance)

Also check for other codes & vacuum leaks anywhere,intake,exhaust
before converter,evap system,pcv hoses

Egr Valve may be a problem also

Need to be more proactive thru out the year & look for problems
not just drive until they happen

Fords have many COP Ignition Coil failures,one or several a year

Need a 20 mile road test with professional scan tool or software
along & 2 drivers to look at data,fuel trim,cylinder misfire counts,
codes not seen by code reader,etc,etc.

Spray Throttle Plate with CRC Throttle Body Cleaner

Oct 09, 2012 | 2007 Ford Expedition

1 Answer

Codes po171 and po174 0n a 2002 ford windstar\

It sounds like you running lean; too much air, not enough gas.
Go to these links to get some additional information:

  • P0171 System too Lean (Bank 1)
  • P0174 System too Lean (Bank 2)

    • The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filtersmag-glass_10x10.gif can cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
    • There could be a vacuum leak downstream of the MAF sensor.
    Possible Solutions

    Possible solutions include:

    • In the vast majority of cases, simply cleaning the MAF sensor does the trick. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
    • Inspect all vacuum and PCV hoses, replace if necessary
    • Check for a dirty fuel filter and proper fuel pressuremag-glass_10x10.gif

    Mar 02, 2011 | Ford Windstar Cars & Trucks

    1 Answer

    How do I troubleshoot service engine codes for 2002 Ford F-150: PO174 and PO171?

    This is the engine lean code. Too much air is entering the engine. Intake manifold gaskets can leak, vacuum lines get old and crack. Check the operation of the EGR and PVC valves, In short it is not easy to find the problem.

    Sep 30, 2010 | 2002 Ford F150 Regular Cab

    3 Answers

    My mom has a 2003 ford windstar and just last week the check engine light came on. We took it in to have it looked and it came up with the codes PO171 and PO174, what can those codes mean?

    it means you may have a big vacuum leak, or the maf sensors little wires inside of it are dirty and need to be cleaned, or the maf sensor failed. Also there is a TSB that says to remove the PCV valve on the valve cover near the radiator, Then remove the little rubber grommet and look inside. At about the 5 oclock position you may see a little hole on the plate that is above the valves . If you see the hole then your suppose to replace the valve cover.
    If all this fails to fix the problem then you need to remove the intake plennun and inspect and replace the gaskets.

    Jan 12, 2010 | 2003 Ford Windstar

    2 Answers

    2002 Chevy Van with a 3400 code po171 too lean how to fix

    Code PO171- Lean mix of Bank 1.
    Code PO174- Lean mix of Bank 2.

    Most of the time a P0171 and P0174 is caused by either a vacuum leak--more than likely the PCV hose and valve or a dirty or defective Mass Airflow (MAF)sensor. Low fuel pressure can also cause this condition. The PCV hose is located on bank one but can affect both sides because the other end is located on the back of the upper intake manifold. Usually they deteriorate and get a hole in it.

    Clean the the MAF sensor with MAF cleaner, which you can pick up at any Auto parts store and also pick up a bottle of fuel injector cleaner. Good luck and hope this helps.

    Nov 16, 2009 | 2002 Chevrolet Venture Passanger

    1 Answer

    Code po171 7 po174

    your computer is reporting bank 1 and 2 too lean, usually caused by the mass air flow (MAF) sensor, you can usually clean this sensor and reset the light. Clean it with electric cleaner or brake cleaner, make sure it is dry before reinstalling, also take care not to damage it. Hope this helps, let me know

    Jun 09, 2009 | 1997 Ford Thunderbird LX

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