• Tiny
  • saltyc1
  • 1917 Ford Windstar

Yesterday, 1/9/07 I asked a question but I forgot to put in that it was a Ford Winstar, 2002 with 3.8 ltr engine.
My interest is this: Bank to lean P171 & Bank to lean P174
Seems like it is comon to both sides of this V6.
What area should I be looking into?

I deleted the MIL lamp and so far in 100 miles, it never came back on. That is so far.
I have 140,000 on it now and I am not sure if any of the emmision sensors have been replaced.
Any help of your knowledge would be appreceiated.
Everything check out so far until I bought a code scanner.


Do you
have the same problem?
Wednesday, January 10th, 2007 AT 4:23 PM

2 Replies

  • Tiny
  • Service Writer
  • Expert
  • 9,254 posts

Here are some possibilities for the code po 171:

Air Measurement System
MAF sensor (contaminated, damaged, malfunctioning, etc.)
Fuel System
Fuel pressure regulator (leaking, malfunctioning, etc.).
Fuel filter plugged, dirty.
Fuel pump (weak, check valve leaking, etc.).
Leaking/contaminated fuel injectors.
Low fuel pressure or running out of fuel.
EVAP canister purge valve leaking (when canister is "clean").
Fuel supply line restricted.
Fuel rail pressure sensor (incorrect reading).
Air Induction System
Air leaks after the MAF.
Vacuum Leaks.
PCV system (leak, valve stuck open, etc.)
Improperly seated engine oil dipstick.
Exhaust System
Exhaust leaks before or near the HO2Ss (exhaust manifold gasket, mating gaskets, etc.).
EGR System
EGR valve tube/gasket leak
EVR solenoid vacuum leak
Secondary Air Injection
Damaged/malfunctioning secondary air injection system (mechanically stuck valve).

Common Ford problem with this code is a dirty MAF.

When your engine is cool, remove the wiring clip from the side of the black plastic sensor part of the MAF aluminum body. To remove the MAF interior sensor wire, you will need a Security Star (Size T15 or T20) screwdriver or screwdriver bit for a power screwdriver. Remove the two security star-head screws and carefully remove the sensor. You will see the two sensor filaments they look almost like the filaments on a light bulb. Carefully spray the filaments with an O2 safe carburetor cleaner, such as Gumout. Let it dry thoroughly. I help mine along with a careful blast or two of canned dry air. While it is drying carefully wipe the aluminum mount surface of the MAF body if there is any dust there, but be careful not to get dust in the mount hole. When the sensor is dry, replace the sensor back in the MAF body and secure with the security star-head screws. These don't need to be torqued down, just simply hand tight. Replace the wiring clip. Then start up your engine.

Was this
Wednesday, January 10th, 2007 AT 4:27 PM
  • Tiny
  • Jack42
  • Member

Service Writer nailed with the MAF. Honestly I havent had much luck with cleaning them. Ford has had such a problem with them that new ones arent available from FoMoCo, they are reman.

Was this
Thursday, January 11th, 2007 AT 7:25 AM

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