This is redundant or obvious to most readers on here, but we still see instances of folks writing about performance/driveability problems and saying they have already 'replaced the MAF' -usually on advice of their mechanic- and it made no difference or the problem came back.
- Mass Air Flow sensors are expensive and usually arent the problem after all.
- They are far more rugged than most think, even though the elements look delicate.
- Since they dont really fail all that much, if you have a fairly popular make, the salvage yards are full of perfect suitable replacements... just have to match them exactly by numbers.
- They DONT WEAR OUT.. but they're sometime subject to electronic chip failure.
Most PCM systems are designed to use an alternate-run paradigm if the MAF fails.
So the BEST thing to do if you have a driveability problem is to disconnect the MAF wiring connector. If the problem IS in the MAF, you'll likely see the engine runs better {remember it wont be as efficient, and the CEL will light} If it runs WORSE, the problem is somewhere else.
Instead of replacing it, CLEAN it first! Unlike the IAC, cleaning usually fixes the MAF problem.
Codes shown on MAF: Think about what the code says.. if like "Out of range" or no Signal: then the MAF or wiring to it is bad.
If it equates to "Too LOW output" try cleaning.
HOW IT WORKS: Measures air flow by tracking current needed to heat the sense element; on dual element types, one measures ambient air temp, outside the air flow.
Dirt on either is like putting heated mittens on a thermometer.