My check engine light came on?

That mean's for some reason that your engine sense's it's running too lean. Most likely you have a vacuum leak which can be difficult to find.A low fuel pressure issue which you would have to get a fuel pressure gauge and see what your fuel pressure was. Or you could have a dirty mass air flow sensor or it could just be bad. The mass airflow sensor is right by your air filter box it's on the tube going into the throttle body. You would remove that and see if there is any oil or residue on the sensor inside the tube. To clean it you would need some cleaner they make to clean them they sell at the auto part's store. To check for a vacuum leak you would need to inspect all the vacuum line's make sure they didn't have hole's crack's split's or not connected. Also you would have to get some carb spray and let the engine idle while you sprayed around the intake manifold vacuum hose's and if the engine stumble's rpm's go up or it die's you have a vacuum leak there. It can be a real pain in the butt to find and fix the p0171 code.

You can give that a try it just best before you replace thing's to rule out the other thing's first. But no harm in trying that.

You need to pull the codes from the computer to see what's going on. Sounds like it "may" be an air metering problem. But need the codes.

There you go i would still be looking for a vacuum leak and checking fuel pressure and all that.

Have you tried clearing the code?If so how fast does the code come back?Also how did you check for a vacuum leak?It's most likely a mass airflow sensor or vacuum leak.

The best way to check maf sensor reading is with a scan tool that way you can see what the computer see's. That way you can see if the wiring from maf to the computer is good. Also vacuum leak's can be very hard to find they can be there one min and gone the next. They can very small and very hidden like the brake booster hose or a hard plastic line that only leak's when the engine torque's a certain way. Carb spray is a good way to check for vacuum leak's but some time's they can be so small you need to smoke the engine and watch for the smoke to be sucked into the leak. The maf sensor can read good one min and bad reading's the next. That is a difficult code to fix some time's you have. Just to give you a example the last person I helped with the same code had a 1989 tempo 4cyl and he even replaced the maf sensor he checked for vacuum leak's like 10 time's checked fuel pressure all that. You know what it turned out to be a bad maf sensor the new one he put on was bad. With the ford's stuff like that happens some the aftermarket sensor are bad out of the box.

That's probably for the better let me know what they find.

Glad to hear you got it all figured out that's what we like to hear. Thanks for using 2carpros.

Hi there,

The check light is a visual indication that there is a fault code in the ECU. You will need a scan to read this code, as it will be an indication as to your problem, start here.

Mark (mhpautos)