Engine air filter - P2 turbo engines not sure on NA

Post by **scot850** » 12 Jan 2026, 23:30

Today, for the first time in a while, I realized I had forgotten to change the air filter in our son's car as part of the major service program. So I decided to tackle that. What a daft design the lid of the air box is. That stupid part where the middle location pin on the back of the lid is actually a semi-hinge is nuts. Due to the fuse box directly behind it you can't easily get the lid off or back on without a fight.

I discovered it must have been there for years as it was really dirty and there was a lot of dirt in the lower section. Took a while to clean it, but when I went to fit the new MANN filter I realized it is different to the OE one I removed. I have never seen one like that before:

: OE engine air filter

On the underside there was a piece of foam stuck on one end above where the cold air enters the box. I can kind-of understand the reason as it is above where the intake air pipe fits which means the filter section above there is likely of little use. However, it still reduces the surface area somewhat. The MANN filter does not have that. Not sure if that will affect the way the engine runs at all.

Neil.

Post by **abscate** » 13 Jan 2026, 03:14

I’m guessing they are mitigating intake noise with that foam, not filtering. The p2 chassis is tomb like quiet, so you have to start chasing new sources of noise to eradicate

Post by **br0dy519** » 13 Jan 2026, 07:41

Safety first with the steel-toe Crocs!

Post by **scot850** » 13 Jan 2026, 17:19

I need the vents to help cool my brain!

I decided to forgo the boots while doing the 5 minute air filter job, the job where it took 45 mins including cleaning the air box as it was full of crap internally. Probably never been cleaned in 19 years!

Neil.

Post by **br0dy519** » 14 Jan 2026, 07:28

scot850 wrote: ↑13 Jan 2026, 17:19 I need the vents to help cool my brain!

I decided to forgo the boots while doing the 5 minute air filter job, the job where it took 45 mins including cleaning the air box as it was full of crap internally. Probably never been cleaned in 19 years!

Neil.

That’s OK, I’m not the best with PPE either. In hindsight welding in my full pipe band kit at 4am after a night of drinking wasn’t the best idea …. at least I took off the prince charlie but fixing the wool with all the welding spatter was time-consuming..

Post by **vtl** » 14 Jan 2026, 08:00

I think this is called a prefilter, and you can find it on "offroad" filters. This foam was stock on my TRD Offroad Tundra, it helps with keeping elements like snow off the main filtration surface.

crasbe · Post by **crasbe** » 14 Jan 2026, 08:37

scot850 wrote: ↑12 Jan 2026, 23:30 The MANN filter does not have that. Not sure if that will affect the way the engine runs at all.

I wouldn't worry about it, MANN filters are quality filters. MANN has been OEM supplier for more than 50 years (at least for Mercedes), so they know what they're doing

But to answer the headline: no, [MANN filters for] NA cars don't have that foam piece either.

It is possible that Volvo put that there because air doesn't flow through air filters 100% uniformly. If you change the filter earlier, you can see spots where there's more and spots where there's less dirt. Putting the foam in an area where there's more airflow, you get a more uniform airflow and more filtration in the filter area where the airflow is higher.