Air filter box

[Gasmonkey]

Hi, I have a 2011 Audi A4 b8 2.0 tdi, when I was changing the air filter I noticed that there is a type of sensor in the bottom of the filter housing, can anyone tell me what this is and what it does?

thanks

[Simon P]

Don't know, but I'd hazard a guess that it measures how much vacuum there is inside the filter, from engine suck. The more yer airfilter is blocked by dust etc, the more vacuum there will be. Once the vacuum reaches a predefined level, an air filter warning will come up somewhere.