A free check from a parts store can't hurt anything. What good it might be would be considered questionable. FORD is the most original rip off company when it comes to identifying and correcting computer and sensor codes. They say "our equipment finds a bad one and it has to be corrected before we can detect another one." I say B.S.
My first impression in this case would first be to research the vehicle maintenance procedure. Many vehicles now require a special mechanical procedure to turn that light off when the regular maintenance is done "supposedly at the dealership by the dealership". If this is the case all you need to do is learn the trick to turning it off and then do it again when it comes back on every so many miles. Just another dealer rip-off trick.
If the free check from the parts store shows anything, it will be related to something a sensor is telling the computer. Often times the oxygen sensor in the exhaust is the culprit and reading the codes will say you have a rich or lean exhaust. This in itself usually isn't a problem because of the terrain we drive and weather conditions.
If the light comes on and flashes before you move the key to the start position, the system should all be operating properly and is probably the maintenance light aggravation mentioned earlier. After having the codes read at the parts store and making written note of what they are for later comparison, disconnect the positive battery terminal for 30 seconds. This will clear all the computer fault codes. Drive it for a few days and have it read again and compare any fault codes. If there are none your'e good to go. If there are some and they are the same, you have a point to begin looking for the problem. A fault code reading in the system will NOT tell you what is causing the problem. It only tells you which SYSTEM is causing the fault. Usually a sensor in the system is at fault and can be easily replaced.
BUT FIRST OF ALL....... Check ALL vacuumm lines for leaks and deterioration. Take them off wherever you can and shorten the ends if they even look bad.
SECOND.....check every visible section of wiring you possibly can. Look for wear spots that could create grounds or voltage leakage, bad connections or corrosion, missing insulation,etc;. You get the idea. 90% of problems can be tracked to aged vacuum hoses and wiring defects and can usually be fixed with little or no cost.
Since you only "suspect" something might not be right, I'd still just ignore the stupid light. I know dozens of people with the same stuck light. For gas mileage, put about 7 pounds more air in you tires than the recommended air pressure on the side of the tire. Drive the speed limit or less when you can and take your foot OFF the gas pedal every chance you get to coast down a hill. I gained 10 mpg just doing that and I ain't gettin' anymore Hundred dollar speedin' tickets either.
