How often should you change your engine air filter

Ask the Mechanic

Wed 15 Mar, 2023

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Your car’s engine relies on three things to run: fuel, air, and an ignition source. The air filter is an essential part of this equation and knowing how often to change your engine air filter is a key part of vehicle maintenance.

What is an engine air filter?

The air filter keeps dust, pollen, and debris from entering your car’s engine. Without the air filter, your fuel system would get jammed with contaminants that damage the engine. Older air filters were a pleated paper design. Newer filters use a cloth or foam medium to trap debris.

The air filter can trap particles as tiny as a couple of microns, providing protection for the engine and fuel system. On older vehicles, the filter was inside a large, round metal housing on top of the carburettor, with a snorkel that allowed air to enter.

Newer cars have a hose that’s four or five inches, drawing air from the grille area and directing it back to the fuel injection’s throttle body. The air filter is located in a box, usually close to the intake at the grille. Some cars have a square or rectangular air filter frame, while others have a conical filter. The filter box lid is usually held on with plastic snaps or a bail, making the filter easy to access.

Engine air filter vs. cabin air filter

The engine air filter is mounted under the hood, toward the front of the engine. Its job is to keep debris out of the engine. The cabin air filter, on the other hand, is often mounted behind the glovebox. It is designed to keep dust and allergens out of the vehicle’s HVAC system where they may cause problems for passengers.

The cabin air filter is typically changed every 10,000-15,000 kms, although sometimes more frequently if you’re in a heavily polluted area or regularly drive on dusty roads. Signs of needing to change the cabin air filter can include:

Allergic reactions or other respiratory problems while driving

Bad smells entering the cabin

Poor performance from the HVAC system

Noisier than usual AC or heater functions

Signs you need to change the engine air filter

When your engine air filter gets clogged, it strangles the engine’s performance. Think about trying to breathe with a damp towel over your mouth while exercising. It’s not unlike what happens to your engine with a dirty filter. Here are some signs the air filter needs to be changed:

A drop in fuel efficiency (although this isn’t always the case because the fuel delivery system can adjust itself to a less-than-optimal fuel/air ratio)