What damage does a dirty air filter cause?

Answer 1

A dirty air filter by itself, will not cause any damage to the engine. However, it is not wise to operate a car with a dirty air filter (or any dirty filter, for that matter), because the performance of the engine will be affected, and the risk to cause it serious damage is greatly enhanced.

An internal combustion engine is basically an air-burning device. The air-fuel mix relation in four cycles gasoline engines is around 14 to 1. It means that the engine requires 14 parts of air for each part of gasoline it burns in order to generate power. An air filter's function is to clean the air before it gets into the engine's fuel injection system, by retaining dust and other particles contained in air. When an air filter gets clogged by dust and debris, air supply to the engine is reduced. This causes poor performance, high fuel consumption and eventually will cause damage to the engine.