Computers control a very large percentage of engine functions. One very important function is how much fuel is delivered to the engine. The computer calculates the amount of fuel that’s needed and when to deliver it. An important part of that calculation is the proper air and fuel mixture. That’s based on the volume, temperature and density of the air.
The Mass Air Flow sensor measures all of those things and reports them to the computer, which makes adjustments to keep your engine performing efficiently. Outside air enters the air intake system, passes through the engine air filter, and then flows through the Mass Air Flow sensor, and then into the engine. When your air filter is dirty, dust and other contaminants get through and end up on the Mass Air Flow sensor.
The resulting problem is that the sensor can become contaminated affecting its measurements. The computer is sending out instructions based on false readings which can affect drivability, your catalytic converter, exhaust emissions, trigger a check engine light, and could even prevent your engine from running.
This brings us back to the engine air filter: it’s truly the first line of defense against some pretty expensive problems. Should your Mass Air Flow sensor become contaminated, it may be possible to clean it during an air induction cleaning service. If the sensor has been damaged, it needs to be replaced.