I am driving along in my 2009 FEH and suddenly see this yellow engine light. I knew from experience it did not mean the engine was about to blow up, but likely that something had gone wrong with emissions. Called a Ford dealer to be sure, that indeed that was the issue. They said there was no rush to fix it, but it might reduce my MPG if I did not, so I went ahead and had it fixed under warranty (though I don't think a part like that should fair in the first 25,000 miles). While they were fixing that they found that my battery was bad and replaced it. I never had a battery fail that quickly.

In any event, since the repair my mileage has dropped. How much it has dropped is a bit of a guess. I used to rely on the MPG indicator, which I found was okay overall, sometimes a little high, sometimes low. Now it is mostly low, showing around 24-25 for all around driving, when actual measurement is more like 26+. Based on the gauge, I was usuall over 27 for overall driving before the repair. On a recent trip I would have expected to get 28-29 and got a bit under 27. Next time I take it in for service, I will have this checked out, but was wondering if anyone else had this issue.

I am pretty happy with the FEH, but my prior Toyota Prius had no repair issues at the same mileage.

 

Can't say I've had the same problem but my wrench icon has come on 3 times in as many weeks. (turns off @ restart) So I'm still looking into that one. Good luck!

 

If you follow GaryG you learn the importance of the KAM. When the battery is disconnected you lose your vehicle's previous settings and need to drive for the vehicle to relearn/reobtain what it had lost. You can purchase a KAM saving device at the big vendor (Walmart) for less than $10.

 

That is interesting, because the mileage has improved a bit over time. I did not realize there was a learning curve.

 

Bear in mind that fuel changes seasonally too and cold air can reduce mileage as well.

 

I doubt if it is a fuel change. The change in gas mileage was too immediate.

 

If you didn't lose your radio stations when the dealer changed your battery, then the kam line doesn't apply. Most dealers, most, will use a device to preserve your vehicles fuel strategy when changing or disconnecting your battery.

With that being said, if you run a little extra air pressure in your tires and also had the feh serviced, dealers are notorious for returning the air pressures to the recommended levels, which is not optimum for fuel mileage.

 

Boy, I agree with Sean's air pressure comment. Went to the Goodyear guys, normally very good about servicing the FEH. Specified I wanted 45psi in all tires. Got it back and immediately went on a trip from GA to NC and back. Mileage dropped by about 2.5MPG. Checked the tires and sure enough, pressure was set at 32. *****ed at them when I got back and their response was, "Oh, we always set them at 32." This in spite of the fact that the work order clearly stated, "customer wants air pressure at 45." Moral: Trust, but verify! Otherwise, they've been great!

 

I guess with those pesky rollover liability cases a few years back they might be hesitant.
By the way which emissions related part set your fault light?

 

Sorry to be so slow in responding. Bad MAF sensor, whatever that is.