What is directly behind an Air filter ? The Mass Air Flow Sensor.
MAFs are sensitive to dirt and debris due to their design. Look at the diagram above, notice the green line, this is a very Very! thin hairline piece of metal, this is generally were it fails due to a dirty air filters.
Mechanic Says: Ma’am your air filter is dirty.
Customer says: My husband says he can do it himself. (so I smile and say OK)
The problem is most of the time husbands don’t do it or the wife don’t tell the husband about the dirty filter. A mass air flow sensor is used to find out the mass flowrate of air entering a fuel-injected internal combustion engine. The air mass information is necessary for the engine control unit (ECU) to balance and deliver the correct fuel mass to the engine. It’s hard to give a specific time or mileage figure because the life of the filter depends on how much crud it ingests. A Good filter
that lasts 20,000 or even 30,000 miles on a vehicle that’s driven mostly on expressways may last only a month or two. Removing the filter and holding it up to a light will show you how dirty it is. If it’s really caked with dirt, it obviously needs to be replaced. Trying to shake or blow the dirt out is a waste of time because too much of it will be embedded in the filter fibers.
p.s Their are more things that go bad with dirty air filters