What is the cause of a dirty mass air flow sensor?

A dirty mass air flow (MAF) sensor is typically caused by the accumulation of contaminants such as dirt, oil, and debris from the air entering the engine. This can occur due to a clogged or poorly maintained air filter, as well as the use of aftermarket oil-based air filters. Additionally, the buildup of carbon deposits and engine oil vapors can contribute to the sensor's contamination. A dirty MAF sensor can lead to incorrect air-fuel mixture readings, resulting in reduced engine performance and efficiency.