Your engine breathes thousands of litres of air for every litre of fuel it burns, and the air filter stops the dust, grit and insects getting in. A clogged filter makes the engine work harder, dulls the throttle response and can cost you fuel. The good news is that replacing it is the easiest job on this whole site.
What you need
- The correct air filter for your car (our Basic Filter Kit, Standard and Major Service Kits all include one, matched to your reg)
- Usually nothing else. Some airboxes are held by screws, so have a Phillips screwdriver or a 7 mm to 10 mm socket to hand
- A cloth or a vacuum cleaner
Step 1: Find the airbox
Open the bonnet and look for a large black plastic box, usually to one side of the engine, with a wide pipe running from it to the engine. That is the airbox and the filter lives inside it. On a few cars the filter sits in a round housing on top of the engine instead.
Step 2: Open it up
The lid is held by metal spring clips, plastic clips or a handful of screws. Release them all, then lift or hinge the lid away. You may need to ease the air pipe a little, but you rarely need to disconnect it. If a sensor plug is in the way, unclip it carefully and remember where it goes.
Step 3: Swap the filter
- Lift out the old filter and look at it. If it is grey, black or full of leaves, you are doing the right thing.
- Before you fit the new one, note which way the old filter sat. Most filters only fit one way, but a few can be fitted upside down by mistake.
- Wipe or vacuum any dirt out of the bottom of the airbox. Do not let anything fall into the pipe that leads to the engine.
- Drop the new filter in, making sure the rubber edge sits flat all the way round. A filter that is not seated lets dirty air past.
- Refit the lid and all of the clips or screws, and reconnect any sensor plug you moved.
How often should it be changed?
Most manufacturers say every two years or 20,000 to 30,000 miles, but it depends on where you drive. Dusty lanes, building sites and lots of motorway miles all shorten its life. A quick look every service tells you more than any schedule: hold the filter up to the light and if you cannot see light through the pleats, change it.
Signs the air filter is overdue
- Sluggish acceleration or a flat feel at higher revs
- Worse fuel economy than usual
- Black smoke or a sooty exhaust on a petrol engine
- The engine management light, in extreme cases
Can you clean it instead?
A standard paper filter cannot be cleaned effectively. Tapping the dust out helps for a day; compressed air tears the paper and lets grit through. A new filter costs a few pounds, so just replace it.
Get the right parts for your car
Enter your registration at easyservicekits.com and we will match the correct oil grade, quantity and filters to your exact engine, check them before dispatch and deliver free anywhere in the UK. Not sure which kit you need? Email hello@easyservicekits.com with your reg and we will tell you.