Your filter should be inspected at every oil change interval. In “normal” driving conditions, change every 20,000 km. Unless “severe” conditions such dusty roads, then change at 10,000 km
The air filter traps dirt particles, which can cause damage to engine cylinders, valves, pistons and piston rings. Excessive clogging will starve your engine of the necessary large volumes of air it requires to mix with the fuel, which may cause loss of engine performance and reduced fuel economy. Your vehicle’s engine uses close to 40, 000 litres of air for every 3.5 litres of fuel burned, so the air filter has a critical role.