- The air filter prevents dirt particles from entering the engine's combustion chamber along with the intake air. If this is not prevented, engine components such as piston rings, sleeve bearings, valves and cylinder walls can be damaged
- If the filter is clogged, the increased vacuum in the intake connecting pipes can draw dust particles from the filter into the engine
- The engine output and torque depend on the air flow. The filter therefore ensures a controlled supply of air
- The filter paper must be securely pleated and impregnated so that it is resistant to deformation and moisture
- Even with good air filters the flow output drops. A loss of output, increased fuel consumption and higher emissions can result from this