Not sure what you are refering to.

Tried to find a picture on web but could not - must take one next time I clean unit!

Basically, I see three parts on the actual sensor after removing from housing:

- Nearest to flange there is an exposed transistor or resistor - probably thermistor?

- Further down, there is a rectangular cavity that passes right through plastic sensor - inside is a mirror like small plate. There is a small hole on one side.

- Even further down, near bottom of sensor, there is a hole on front side of sensor facing air flow - it does not pass all the way through. There is some type of element or device inside - hard to get at and clean.

It is the last one that I was asking about.

Tried to find technical data from Bosch sites, but they only describe a different (newer?) type with a method of separating particles and water droplets ahead of the sensor.

Not to worry - just trying to understand better how cleaning may help and on which parts .