So i'm sure each and every Superb MK3 and any other MQB platform car including Golf's, Passats and such have came across the following fault
1 Fault Found:
263425 - Air Quality Sensor
B10AF 04 [009] - Internal System Fault
Confirmed - Tested Since Memory Clear
And the only solution is to replace the Air quality sensor, located in the plenum chamber.
The part numbers for the superb went in the following order
5Q0907643B was the original up to 2016.
Since then the part number has been revised with the letter at the end changing, going to C,D,F and then finally as of 2023, the newest part number is 5Q0907643E.
The part has its own self diagnosis and is non servicable so its simply a case of removing, replacing and clearing the fault codes, but no one actually knows what the common issue is.
Now onto the part itself - 5Q0907643D dated 05-06-2017:
The air quality sensor also called AQS is fitted in the cabin air intake and detects pollution in the incoming air including emissions and pollen - It then feeds this back to the climatronic control module via the LINbus and in turn this automatically switches the air to recirculation. That is as simple as the process can be.
The outside of the part consists of a completely sealed plastic casing, 3 pins (12V, ground, LINbus) and an air intake with a white membrane over it.
The part needed to be cut open to access the internal circuit board which was done with a very small hacksaw.
Inside we had a small double sided circuit board as pictured below
The components on this circuit board are as follows - as well as what I could possibly test, has been tested.
Various resistors - couldnt find a single one burnt out, okay
Various capacitors - couldnt find a single one burnt out, okay
16F1938 micro controller - Unable to test but this is the main control unit for this component and if it was faulty, there is a good chance we wouldnt get the above fault code - instead no comms
A voltage regulator - same diagnosis as above
LINbus controller - same diagnosis as above, would not have any comms if faulty
And then the 2 very odd things on the ends of the 'fingers' almost..... see below
So on closer inspection you have these 2 very small black boxes, each with 4 connections
I have no idea what these components are, but they seem to be some kind of optical sensor, but on an extremely tiny scale. I assume these are what pick up the particulates and tell the control unit there is a high pollution level - but this is just speculation.
Now I done my best to get an up close picture of the sensors and their connections, but on my phone camera this was almost impossible, but this is the best I can do.
Youll notice each of these components is isolated from the ground plane (light green part of the circuit board) and on each of the black boxes there are 4 very small gold dots on top. I have nothing to measure these with but a guess would be 0.1mm each.
These are the connection points from the component to the circuit board.
You will also notice that to connect the circuit board to the component is an absolutely TINY gold wire (can be seen on closest component bottom right connection). These are so much smaller than a human hair even, impossible to measure with any tools I have.
Most of these tiny gold wires are snapped off at one or both ends!
So for the top component - the top 2 wires are completely missing, the bottom 2 are still connected.
The bottom component - the top 2 wires, one is detatched from the circuit board, the other is missing. The bottom left is not touching the circuit board, the right is connected only to the circuit board.
So basically, these wires that are maybe a 10th of a human hair. Of the 8 connections, 2 are doing their job.
And here lies the issue! These components and their connections are so fragile, being in an engine bay is enough to completely destroy them.
Would be very interesting to see a newer revision and what has changed internally.