Can I change my engine air filter myself, or should a garage do it?
Do it yourself. A garage charges £30-60 to change an engine air filter that costs £8-20 and clips out in ten minutes on most cars. Pound for pound this is one of the biggest markups in routine servicing, and it needs no tools on many cars, or at worst a screwdriver.
How hard is it really?
Genuinely easy on most cars. The filter lives in a black plastic box (the airbox) on top of or beside the engine, held shut by metal clips or a few screws. Pop the clips, lift the lid, note which way round the old filter sits, lift it out, drop the new one in the same way, close the lid. That's it. There's nothing electrical, nothing under pressure, and nothing that can leave you stranded if you're slow at it.
Two small things to do properly. Wipe or vacuum any leaves and grit out of the bottom of the airbox before the new filter goes in, because the whole point is keeping that stuff out of the engine. And make sure the new filter seats flat all round its rubber edge before you clip the lid down. A filter sitting proud on one corner lets unfiltered air sneak past, which slowly sandpapers the inside of your engine.
Garage price vs the filter itself
| Garage, fitted | Filter only | You save |
|---|---|---|
| £30-60 | £8-20 | £22-52 |
Look at those numbers again. The labour content of this job is five to ten minutes, and you're being charged up to £50 for it. It's also a classic upsell at service time: "your air filter's dirty, want us to do it while it's here?" A slightly grey filter is normal, by the way. They're meant to catch dirt. Replace on the schedule, not on the colour.
The one way to get it wrong
Buying the wrong filter. This is the only real risk in the whole job, because airboxes differ between engines in the same model, a 1.0 petrol and a 1.5 diesel Focus take different filters, and a wrong one won't seat properly. Always buy by your registration number, not by "it's a Focus". Online, the filter itself is £8-20; run your reg through the part checker and stick to known names like Bosch, Mann or Crosland rather than the cheapest unbranded one on the page.
When you should NOT DIY this
Rarely, but it happens. A few engines bury the airbox under plastic covers or pipework with awkward fixings, and some diesels want half the intake ducting disturbed to get the lid off. If you open the bonnet and can't see obvious clips on a black box, watch a two-minute video for your model before deciding. The other case: if the car's booked in for a full service anyway, the air filter should be included in the service price. Don't pay a separate £40-60 line for it on top, and don't accept it as an "extra" on a service that's supposed to include it. If that's happened to you, see our overcharging guide.
If a garage does it, what's fair?
£30-60 all in at an independent is the going rate, and towards the bottom of that if it's done alongside other work. As part of a full service it should effectively cost you the price of the filter. A dealer charging £80+ for this one job is charging a full labour hour for ten minutes' work, which tells you plenty about the rest of the invoice.
Common questions
How often should an engine air filter be changed?
Every 20,000 to 30,000 miles or roughly every two to three years for most cars; check your service schedule. Dusty routes, unpaved lanes and lots of town driving clog them faster. It's included in a full service, so most drivers never need to buy one separately.
What are the signs of a clogged air filter?
Slightly sluggish acceleration, worse fuel economy, and on older cars a whiff of over-rich running. Modern engines compensate well, so symptoms are subtle until the filter is properly choked. A quick look tells you more: heavily darkened, debris-packed pleats mean it's due.
Will a new air filter improve my MPG?
A little, if the old one was genuinely clogged. Tests suggest modern fuel-injected engines lose more performance than economy, since the engine computer adjusts fuelling. Don't expect a transformation; expect the engine to breathe as designed. It's maintenance, not a tuning upgrade.
Are performance air filters worth buying?
For a normal road car, no. Cotton or foam performance filters cost several times more, need cleaning and re-oiling, and over-oiling can dirty the airflow sensor and cause running faults. The claimed power gains are tiny on a standard engine. A quality paper filter is the smart buy.
Is the engine air filter the same as the pollen filter?
No, and people mix them up constantly. The engine air filter cleans air going into the engine and lives under the bonnet. The pollen (cabin) filter cleans air coming into the cabin through the vents and usually hides behind the glovebox. Cars have both, changed separately.