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.
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.
My friend has the scan tool, so I can just borrow it from him again and clear the codes. As far as engine performance, it never felt bad. I believe the sensors look more shiny after lightly scraping them. Last time I cleared the codes, it took about a month before the light came back on. So, I guess I’ll see if this worked in about a month. Thanks very much.
You will need to clear the codes with a scan tool, disconnect the battery to possibly clear the codes or wait about 40 key cycles for it to clear out on it’s own. Can you tell any difference in engine performance? Did you find much build up?
Excellently described. I performed the above MAF cleaning. Unfortunetly, when I started my 2003 Windstar, the check engine light is still on. Does it take time or should it have gone out immediately?
Hi Kan,
I am near Charleston, SC which is a long way from where you are. I assume you were referring to cleaning the MAF sensor. This takes about 30 to 45 minutes. Since your vehicle is low mileage, I don’t think that cleaning the MAF will help much. Instead I would recommend having a local shop do a leak test on the intake plenum. You will need to ask your shop if they can do this kind of test before taking it in.
Thank you for taking the time to respond and for your website showing your repair of this issue. About how much would it cost to have you do such a repair as illustrated in your website? Also where is your shop located. We are near Chattanooga, TN.
Thank you:)