Ford Windstar Lean Code – P0171 or P0174

9:48 am DIY, Ford Problems, How To Auto Repair, Lean Codes

Summary: This auto repair blog post provides a quick easy way to check for a vacuum leak that can cause lean codes on Ford Windstars.

Ford seems to have more than it’s reasonable share of lean codes, the Ford Windstar is no exception. If all the usual suspects have been investigated and no leaks were found, there’s another possible cause of a lean code when diagnosing a Ford Windstar. At one time I had so many of these vehicles to work on… I kept a parts list! In my notebook, I kept a list of part numbers that made writing up an estimate for repairs much easier. Later, when I used the computer at work more I converted my notes over to a “Word Document” file that allowed me to copy paste. When you work Flat Rate, you learn to save time when you can!  Back to the subject at hand. In this auto repair article we briefly cover a common cause of lean codes on the Ford Windstar.

We recently wrote a repair article on Common Causes for Lean Codes and what to look for, that may also be helpful. This article covers a specific problem that many Ford Windstars have. Lean codes can affect both banks or just one. The intake manifold on the Ford Windstar has intake runner seals that are prone to leak. The runner seals, most of time can be checked easily with fuel injection spray. All the basics should be checked like in our other article, but if nothing else is leaking, chances are one of the intake runner seals will be the cause.

**Caution** When spraying the intake runner seal be sure to stay clear of the alternator to avoid starting a fire! If a change in idle or stumble results when spraying the seal, it has a vacuum leak. The one being sprayed in the picture above is in the front, don’t forget to check the back one as well. P0174 a lean code for bank #2 which is near the radiator on the Windstar. Lean code P0171, is a lean code that affects bank #1 which is near the firewall. If both codes are present, then obviously both of the intake runner seals are leaking or a different problem is the cause altogether.

Question: How do I remove the upper plenum? It’s a tight fit to remove it, because of it hitting the wiper cowl.

Answer:It is tight, but it can be removed without removing the cowl. When loosened, rotate the right side of the upper intake towards the front of the vehicle. Go easy because breaking the plastic channel is a possibility if it is forced.

Question: Do I have to replace the entire lower intake due to the seal leaking?

Answer:I dealt with aftermarket warranty companies, that were willing to pay for the entire intake. So, I never resealed the intake runners myself. I do know of a few other auto techs that were forced to reseal them occasionally because of the intake assembly being on back-order from Ford. Unbelievably, they used air conditioning o-rings to replace the ones that were leaking and they never had any comebacks that I’m aware of.

20 Responses
  1. Henery Schaffer :

    Date: August 22, 2009 @ 10:00 am

    I’ve been reading along for a while now. I just wanted to drop you a comment to say keep up the good work.

  2. dennisb - Auto Tool Sales :

    Date: August 22, 2009 @ 10:08 am

    Henery, Thanks. By providing information that people can actually use (unlike a lot of useless content found on the Internet) people are bookmarking us increasingly. They also are signing up for the RSS feed to get notifications when we have new articles posted. Our sales have increased by featuring automotive tools for specific jobs too. Again thanks again for reading!

  3. Jack S :

    Date: September 2, 2009 @ 4:03 am

    Had this problem with my van, took it to three shops. No one found the problem and the lean code kept coming back. After researching this problem on-line I found your site. I was able to fix my car myself and save a ton of money. Thanks for all the great information!

  4. Bob, independent shop ASE Master tech 32 yrs exp :

    Date: January 7, 2010 @ 8:49 pm

    I have noticed that lean codes are more common in vehicles built after 2000. Computers are reporting codes P0171/P0174 at a lower fuel trim deviation than in the past (18% vs 25%in the 90’s). The problem is not just with Ford. Auto makers must have forgotten lessons learned from Chryslers 1977 Lean Burn Engine. Engines need good seals and fuel systems need wiggle room.

  5. Robert Z, :

    Date: April 1, 2010 @ 8:45 am

    My daughter lives in North Carolina, her husband is deployed with the Marines. She has this lean code problem. I live in Milford P.A. will she be able to drive her Windstar van here so I can fix it for her,or will something catastrophic happen? She has to travel with a 3 month old a 2 yr. and 3yr old. Any help will be greatly appreaciated.

  6. dennisb - Auto Tool Sales :

    Date: April 1, 2010 @ 11:09 am

    Robert, first of all please thank your son in-law for his service to our country.

    Most times with a lean code, the engine just runs rich and not as efficient. Your daughter should be able to tell you if she is comfortable enough with how the Windstar is running right now, to make the trip. If there’s a large enough vacuum leak the engine may stall when coming to a stop. A small leak may go hardly noticed – with the exception of the SES light on.

    As far as something catastrophic happening… anything is possible on a road trip with a car full of small children! Ha Ha.

  7. donald bouille :

    Date: April 28, 2010 @ 9:01 pm

    I gave my trusted tech $500 week before last to replace the intake gaskets. The light came back on driving home from work today. Any clues as to what to do next?

  8. vince smith :

    Date: December 30, 2010 @ 9:44 pm

    i fix the lower intake manifold with brand new runner drove it customer was happy with it then he droveit all over place then it came back on again same codes po171&p0174 lean codes he spend 1500 dollars on it i think should have recalls on it i could not figure POS with 3.8liter look like made from junk yard

  9. dudley adcox :

    Date: March 28, 2011 @ 5:19 pm

    thanks what a great piece of imformation i truely appreciate it, that linkage in the top picture, what does it do? i have both codes and the linkage was off along with a cylinder two misfire, thanks again for your help

  10. dennisb - Auto Tool Sales :

    Date: March 28, 2011 @ 5:50 pm

    Dudley, The (IMRC) Intake Manifold Runner Control helps to manage the fuel and air mixture for better efficiency.

  11. dudley adcox :

    Date: March 29, 2011 @ 5:36 pm

    dennisb, thanks again for your help I replaced the intake gaskets because there were signs of a leak, although the van runs better and the light didnt come back on yet, the fuel pressure right out of the tank is 50 lbs and while running the gauge reads 30 then once i disconnect the regulator hose it comes up to 40 lbs can you give me a tip thanks again for your help.

  12. Joe Chapman :

    Date: April 29, 2012 @ 5:02 pm

    I noticed that the van has been sputtering, is this a cause found in both codes appearing for both banks lean? I have a 2002 ford windstar.



  13. larry :

    Date: November 28, 2013 @ 10:00 am

    I have the bank one bank two system codes. I change the fuel filter the air filter and the elbow the goes on the top of the oil manifold. It started to drive 100 percent better. But last night put a half a tank of gas in it wouldn’t crank for almost an hour. What do you suggest I do because of another Ford I had before that I replace 02 sensors upstream downstream everything and it did not fix the problem until I change a fuel injection regulator.. Right now I’m having a hard time trying to find out where it is on the vehicle. Ford Windstar 2000 3.8 engine..

  14. dennisb - Auto Tool Sales :

    Date: November 29, 2013 @ 1:12 pm

    You may want to check a service manual for your specific model, but the regulator is most likely on the FI (Fuel Injector Rail). If I was checking the vehicle, I would do a fuel pressure test when the no start problem is occurring. It may just be the fuel pump failing.

  15. Rory :

    Date: December 13, 2013 @ 4:45 pm

    Article was helpful. Done replaced a lot of things on out 01 Windstar and recently discovered this leak. Was told by Ford my only option was another Intake.

  16. dennisb - Auto Tool Sales :

    Date: December 13, 2013 @ 4:53 pm

    Rory, yes that’s the normal option. I remember before when I worked at Carmax, the tech that worked beside me had one to do but they were on backorder. He actually took the old intake apart and replaced o’rings or some type of seals. Not sure how long that would really last but it could be an option if you’re willing to risk the time and expense of intake gaskets, coolant etc. Good Luck.

  17. NashvilleDave :

    Date: May 26, 2014 @ 2:12 pm

    from experience: for my 2002 Ford Windstar (180,000 miles) replaced isolator bolts 3 yrs ago b/c of lean codes…solved….P0174 and P0171 codes returned AGAIN last yr….replaced lower manifold gasket….solved……P0174
    & P0171 return AGAIN this year….i thought is was a vacuum,leak…it wasnt…..old MAF showed continuity so I thout it was ok….cleaned wit MAF cleaner…still showed codes….replaced MAF with this part…..SOLVED…no more lean codes…

  18. Josh :

    Date: April 19, 2015 @ 2:26 pm

    First thank you for taking time to write this blog for poor shlubbs like me that aren’t very mechanically inclined but can’t afford to go to a shop for every thing. Second is there a temporary fix our something I can do to get my 02 Windstar to run slightly better for about a week until I can get it into a shop? I have replaced the EGR valve and DPFE sensor and check all usual suspects for vacuum leaks so I’m pretty sure it’s the intake manifold gaskets and isolator bolts bushings. I looked up the fix for it and I’m not equipped for this big of a surgery.

  19. dennisb - Auto Tool Sales :

    Date: April 20, 2015 @ 7:45 am

    If it is the isolator rubber bushings you may be able to take it apart in about 20 minutes and reseal with right stuff sealant. Usually though the leak is where I wrote about in the article (the runner control seals). Sorry there’s no magic wand to wave to make the computer believe there’s no vacuum leak. Good Luck.

  20. Paul Keaton :

    Date: July 11, 2016 @ 12:27 am

    I have been having a problem with these codes along with the codes for the intake manifold runner controls sticking open. I read about a test where I manually move the imrc to the closed position and use my finger to plug the vacuum port. I then released the lever to see if it stayed in position. The one on the radiator side completely failed (it snapped right back to the open position. The one on the firewall side move back some, but not all the way. I replaced the one on the radiator side, and it has helped some, but I still have code p0171. I did a comparison on the test on the old ones to the new one. There is a big difference between the new one and the one I have yet to change so I plan on changing that one too.

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