2001 ford expedition 125k miles P0171 and p0174


Asked by Jul 13, 2014 at 04:24 AM about the 2001 Ford Expedition

Question type: Maintenance & Repair

Can't find the problem
•I replace the pcv hose
•Clean the mass air flow
•Replace the fuel filter (old one
wasn't bad)
•Sprayed the whole car with carb
cleanner and nothing
•Replace the throttle body gasket
The truck has no problems at all runs
good and smooth. One the check
engine light come one it uses more
fuel. Please help

9 Answers


Try replacing your PCV valve. If clogged, it may be gumming up your air filter with oil. If you get your PCV valve out, shake it. If you don't hear the ball bearing rattle, that means it's plugged and not working. Spray some carb clean through it, and shake it again. Usually that will free up the ball inside.


Thank for replying . I replace the pcv and the hose but the check engine light keep coming


Not a Ford guy but don't you have to try and clear the codes before they will go away? Have you tried disconnecting the negative battery cable for a few minutes to see if they will clear?


CAUSE 1: PCV Tube's rubber elbow (where it connects to the intake manifold) is torn open and causing a major vacuum leak. CAUSE 2: intake manifold gaskets that are leaking vacuum. CAUSE 3: fuel pump that's going BAD, but hasn't completely fried yet. CAUSE 4: A dirty (contaminated) MAF sensor. CAUSE 5: An exhaust leak right before the pre-catalytic converter oxygen sensors. CAUSE 6: BAD pre-catalytic converter oxygen sensor.

1 of 1 people found this helpful.

Forgot to mention...the above is a list of possibilities that I cut and pasted from an error code site. Hope it helps....

1 of 1 people found this helpful.

Thanks for all your help. I disconnect the negative battery often. I did replace the pcv hose and clean the mass air flow.


Does anyone live in arizona and know a mechanic that specialize on this?

Need to clear the codes with a diag reader tool. Disconnecting power won't do.


@drfunone just for further reference I have cleared codes both with a scan tool and by disconnecting the battery. the one step that is not mentioned is that you must disconnect both the positive and negative terminals and then touch them together. I prefer to use a jumper wire with alligator clips at both ends. leave them together for about 30 seconds and that has always cleared codes for me. the thing that most people forget is that the electrical system of a car has capacitors in various parts that may allow the system to remain charged for a period of time, by touching the terminals this wil eliminate the residual charge in the system.

2 of 2 people found this helpful.

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