Mass Air Flow Sensor
 

Just to let folks know. I removed my Mass Air Flow Sensor from my V40 2002
Cleaned the sensor with special cleaner off Ebay and refitted the vehicle runs even better.
I do this every time I carry out an oil change every 5k miles

How does it get " Dirty" ? Its fed with clean filtered air .... and is cleaned every time you turn off the ignition ( It glows white hot ) Be very wary of doing anything with your £300+ Air mass meter i have seen them ruined by doing this .

Air Flow Sensor
 

I got the tip from Scotty Kilmer of Youtube. Are you correct it glows hot when engine is off?

Yes on the ones up to around 1991 with the wire filament the later are solid state but still with a hot surface ...

I've cleaned many a grubby MAF in this way on Volvos and other cars, never had a problem and it's always improved the behaviour. The air being drawn past the wires isn't perfectly clean as the relatively cheap and crude filter used don't 100% scrub the air. Nor is the unit hermetically sealed. After thousands of hours there will always be unwanted particles in there affecting the performance.

Have you noticed how clean the inner surfaces of the air filter cover and the air inlet pipes are from the air filter element to the point where the Breather fumes are admitted ? "dirty" air mass meters are just not a problem on the many thousands of Volvos running around out there on the roads ... Mainly people spray stuff on perfectly good clean air mass meters when the problem is something else I have found ...

air mass meters
 

in my experience with a 940 and an s40, the Air Mass metres are pretty much immortal..the only prob I ever had was with the connections to them, just a misaligned pin or the pins not being 100% tight/well fitting. I put a large tie around the one on the 940 and had no further problems. I have two spare Air Mass Meters I pulled out of cars in 2002 and have never used. The wire heating/burn off when the engine is switched off is a very cool Bosch system which is very robust in my experience...

I totally agree , until someone "cleans" them and ruin a good £300 Air Mass Meter ....

My previous V40 did 370,000mls without ever cleaning the maf. Ran like a dream until rust killed the body.

I'd like someone to explain how they think the air mass Meter get "dirty" with clean highly filtered air going through them ...