[smilintodd]

Hey guys, I recently had some trouble with my 2006 Ford Focus. It was giving me a P0171 code for a lean condition. It ended up being a piece of fuzz on the mass air flow sensor. After removing and clearing the code, check engine light went away and drove wonderfully for about a week. Took the car across the state this past weekend and it started acting up. No check engine light but it seemed to have a lack of power, at one point I couldn't get it above 60 mph going up a hill.

My question is, if the MAF sensor is bad, would it turn on the check engine light? Since my original problem was with the MAF sensor I'm leaning toward just replacing it, what do you guys think.

 

[BC_ZX3]

My question is, if the MAF sensor is bad, would it turn on the check engine light?

Generally seems to depend on how it fails. Low voltage and high voltage conditions are monitored by the ECU (lower and upper limits) and throw a code. Other conditions - like your debris on the MAF - may cause other unrelated codes.
Just replacing it on a hunch can be a pricey proposition. Lack of power could be a lean condition resulting from a vacuum leak. Which leads to: Is the MAF seated properly in the intake?