One of the swap it and see parts Mad really..............
It is a silcone chip, that flexes under the pressure ( calibrated of course to application) They can also be used on vacuum too as well as Positive pressure.
Really basically as the chip flexes it alter's it's resistance, and outputs this as voltage, usually low, in VAG cars case 0-5V iirc........ @ least thats how they worked on my ford RS's, busted the fecker messing with one lol, and that was not the fault
was W/G actuator sticking LOL