2003 Ford Windstar P0171 and P0174, Banks 1 & 2 Lean

This 2003 Ford Windstar came in with the service engine soon light on. Checking code revealed codes P0171 and P0174, banks 1 and 2 lean. I checked for vacuum leaks and none were found so I moved on to the Mass Air Flow sensor. It is common for them to get dirty and cause these fault codes. The MAF sensor is located inside the air filter housing so it had to be removed. I loosened both hose clamps and pulled the rubber boot from the throttle body and then from the air filter housing. Then I unlocked the spring clamp that holds the two halves together.

The crankcase ventilation tube also had to be removed from the rubber hose and more importantly it has to be put back in place during assembly. You can see it just to the left of the master cylinder.

After unhooking the wiring harness connector I took the housing to the bench for dis assembly. There are several locks that have to be released. I used a common screwdriver blade to pry them inward while pushing the sensor out from the other end.

There is also another wiring subharness that has to be removed. It is kind of a pain but I take my time so as to not cause any damage. Once the two halves were separated I removed the sensor from the housing using and tamper resistant torx bit socket.

This is were the actual sensor elements are located and in most cases you will find a build up or film on the element. I use a pick as shown or a small screw driver and very lightly rub the film off. Sometimes if it is heavy it will lift off in one try but most of the time it takes a little while of very light rubbing to remove the film. Some people use cleaners but I prefer to manually rub it off so as not to cause and damage to the sensitive parts. Many cleaners will damage the plastics.

Expedition 33

Just several different pictures of the same sensor. There are two elements inside and the most problematic one is the one further inside that you cannot see.

This is just one of the possible causes. There are many and one of my readers left a link to a repair site that has more answers on this problem.

Ford has a TSB out on this for 1999 to 2003 Windstar. if you want to do it yourself, you need to go to your local parts store or dealership and ask for a “Valve cover repair kit”. This site link gives step by step instructions for the fix.

55 discussions on “2003 Ford Windstar P0171 and P0174, Banks 1 & 2 Lean”

  1. Sparky,this is for Urbie.2yrs ago I worked on a lady’s 2003 with same codes with a #3 misfire.Brakeclean told me it was the infamous intake leak.During disassembly I also noticed the IMRC linkage was wired together on one side and link from other side was missing.You can’t buy the links seperately but will come with the new actuator(big bucks there)Now,you can get them at the salvage yard,just remove them from actuator but chances are the little plastic pop in bushings will break.Replacements from Ford only(8.00 a popx4 I don’t think so)E-clips work fine,just a bear to get on because of tight fit.
    There is no spring tension on the butterfly plates to keep them closed so if the link has come loose from the actuator, who knows what position those plates are in.I would think some sort of driveability issue.

  2. That box is the IMRC (Intake Manifold Runner Control) actuator. The retainers can usually be gotten from a Ford dealership. Under certain conditions the PCM will open the runners to improve high speed engine performance. In most cases is is not active below 3000 rpms. It is good that you fixed it but it may have little bearing on the P0171 and P0174 codes.

  3. Something else, light back on w? Same 2 codes? Weird after 2 months and 800miles.
    I found, right behind alternator, attached to side of engine, a box that on the back are two lever action rods. One came off of the back of this unit? The other, the retaining clip broke, tight space, managed to place a small locking washer? What is this box? What is this box? What do the two pulley rods do? One inserts under manifold, onto sometype of actuation lever? The other the same but just before the engine block ends, before a sparkplug? Its dark, one # on unit I think reads? PET-GF30?
    another # is even harder to read, ?e-AJ559AC?
    Would these two pulley that have come loose be the cause of error codes …P0171 / P0174?
    I can’t see where the one to the left inserts into the back of this box? Help please.

  4. All OBD 2 vehicles have to be driven through several drive cycles to allow the monitors to retest the individual systems. After all monitors have completed and passed a vehicle is ready for emissions testing. Ford vehicles will keep a code P1000 until all tests have finished and passed.

  5. I cannot thank you enough… After replacing all oxygen sensors, spark plugs and wire set (this was a good thing anyway) and $300 to a mechanic who made the light go oit for about 2 weeks. And Right before I drppoded my 2003 windstar at the dealer; who quoted $750 to repair and replase Mass Air flow Monitor, and run diagnostics, etc.
    Well, 1 month later, the Van passed the smog test here in CA. With flying Aces!
    The info, and detail is superb! I am currious, I drove the van around for the month after having the engine code reset as I presumed I needed to let it cycle for a while? Was that true or there are are no preset miles one has to drive to completely cleaar all past codes?

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