There’s a funny smell in my car. Do I need a new car cabin air filter?

car cabin air filter

The ventilation system in a car involves a great deal of pipework and is a moist warm environment. That’s perfect for bacteria to thrive and so it’s no surprise if it starts to pong. Here’s where the nasty niff might be coming from.

Where do smells originate?

Bacteria can build up in the darker recesses of car ventilation systems, particularly if you switch off the air-conditioning during the winter. Keeping the air-con working does prevent this from happening.

Try an anti-bacterial cleanse

Take your car to a garage or fast-fit outfit and they can perform an anti-bacterial cleanse. It sounds complicated but actually it should only cost somewhere between £20 and £30. Afterwards you’ll be pleasantly surprised at how fresh the air coming into your car smells.

Might it need a new car cabin air filter?

The car cabin air filter (sometimes called a pollen or micro filter) is at the heart of the heating, ventilation and air-conditioning system (HVAC in car industry talk). This removes dust, debris and pollen from the air that the system sucks in from the outside. You can usually tell when a filter needs replacing because the flow of air into the cabin is constricted or smells stale.

What are car cabin air filters made from?

Car makers employ a variety of materials to make these filters. Some use layers of fleece. Others deploy a folded paper-like material. Yet more have a carbon element in them that’s designed to prevent bacteria and fungus building up. What all have in common is that as time goes by, they will start to get blocked and need replacing.

car cabin air filter

How much do the filters cost?

This depends on the type of car you’ve got. Those for a mass market model using a non-manufacturer ‘pattern’ part might cost as little as £5. Those for a premium model might cost more than 10 times that. Usually, the price is somewhere around the £20-£30 mark.

Can you do DIY replacements?

The answer to that really depends on the kind of car you’ve got. Some car makers ensure it’s simple. Some don’t. Looking at your car’s user manual should tell you if it’s a job for the DIY enthusiast or requires a bit more specialist knowledge.

If the filter is hidden away in the engine bay and requires tools to get at it, best leave it to the professionals. If on the other hand the cabin air filter is easily accessible, you should be able to order the part online using your car’s registration number or vehicle identification number (VIN, otherwise known as the chassis number.) Changing the filter might then be as simple as unclipping one part and replacing it with the new one.

How frequently does a car cabin air filter need changing?

Again, this depends on the car and where you drive it. Usually it’s somewhere between 15,000 and 20,000 miles. But if you cover a lot of miles in a built-up, polluted or dusty area, or the driver or a passenger suffers badly from hay fever or other allergies it might be sooner. The filters can trap particles as small as 0.001 microns. That’s about 100,000 times finer than a typical human hair. Hardly surprising dirt blocks them up.