I have a 2002 Ford Explorer Sport Trac with 72,000 miles and the service engine light just came on.
I read the codes with an OBDII code reader and it gives me the codes PO171 and PO174 "system to lean on bank 1 and 2".
Has anyone seen this before and can you tell me what it means and how to correct the problem?

 

that could be a low fuel pressure problem or a plugged fuel filter. if you have never changed the fuel filter thats where I would start

mountaineer man

 

Thanks for the info, I will give that a try and let you know how I made out.

 

I will bet anyone $1,000 it is bad intake manifold gaskets/o'rings. Any takers? Ford extended the warranty on this to I think 6 years, 60,000 miles. You might be over mileage but I waould ask the dealer anyway. If the first one says no, try another.

 

most of the time with the manfold gaskets you will not cause code from both banks a the same time plugged fuel filter or low fuel pressure will.

mountaineer man

 

From what I've been reading, most of the time the gaskets do show both sides lean. When it first starts out, maybe just one side. When it gets bad enough, both sides - also the same time when it starts idling bad. Been about a dozen or so posts recently in this forum and some others that I monitor as well.

But sure for troubleshooting, both sides lean you would think about what affects both sides. I'd also throw in the MAF sensor to that logic. And this particular problem may be any of these mentioned issues.

But if there was a bet placed, my money would first go to the gaskets....

 

i had the same problem it could be just about anything from a bad gas cap to a blown gaskets it took me about a month to find out that the bosch plantum spark plugs where the problem if you have bosch platnum plugs in there take them out right away

 

Whatever is causing the problem does not seem to be affecting the way the truck runs. It has always had plenty of pep and still continues to get great fuel mileage? I bought a new fuel filter and will try changing that first and checking the fuel pressure, somebody else mentioned checking the screen in the mass flow air sensor as well. I figure I can start with these and try a process of elimination.

Thanks.

 

JM, also check the airtube between the MAF and throttle body for loose clamps, cracks, etc; any opening where air can enter. Any air leak there will set those codes, since the extra air isn't metered by the MAF.

Check the intake bolts/nuts too. If they're loose that will allow leakage by the manifold gaskets. They are a low torque bolt, something like 89 INCH lbs.

If everything else checks out, then it's time for new intake gaskets.

(Just a personal thought; I think it's the composite intake manifold that warps from heat/cool cycles and causes the leaks, rather than gasket failure. Regardless, new gaskets seems to fix it.)

 

My problem started with PO174 with a light miss at idle and progressed to low power (won't run above 12oo rpm) and then no-start unless throttle is held to the floor and then it starts and dies. Any ideas? Engine just replaced with a Jasper bebuilt unit.