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.

 

Edited 24 October, 20241 yr by ApertureS

Nice write up!

Didn't know it auto switched to recirc?

I'm still confused why the internal air filter has to be turned on all the time through the climate menu and isn't just on

Just now, PlatinumCupraR said:

Nice write up!

Didn't know it auto switched to recirc?

I'm still confused why the internal air filter has to be turned on all the time through the climate menu and isn't just on

What do you mean turned on? 
All air will always go through the pollen filter whether it’s on recirc or not.

Do aircare cars have different sensors? Mine isn’t aircare so unsure what the actual difference is tbh

9 minutes ago, Danoid said:

Do aircare cars have different sensors? Mine isn’t aircare so unsure what the actual difference is tbh

Aircare is a software thing, nothing to do with sensors.

 

Its something to do with blowing the air high and sucking it back in through recirc basically.

 

Air quality sensors are fitted on any car with climatronics (2 or 3 zone)

Were these failures an issue on the S2 Superb? I ask as the system in ours worked brilliantly and having looked on the S2 forum, I can’t even find it mentioned? (Preps to get inundated with 658 threads!). 

You are the man! What a great topic! Now the question is ...could it be repaired? Where do you buy gold hairs? 😝

I'd have a go at repairing one, under the microscope. Might be quite tricky, but could be fun to try.

Probably wouldn't use gold wire though, unless someone wants to treat me to 10cm of 0.1mm for £32 https://www.ebay.co.uk/itm/114870867902 😁

 

 

 

 

55 minutes ago, leolito said:

You are the man! What a great topic! Now the question is ...could it be repaired? Where do you buy gold hairs? 😝

So my thinking of the gold wire instead of solder is that it is laser welded on.

 

The component is probably extremely sensitive to heat so just soldering a jumper wire would probably damage the component.

 

that being said, it’s dead anyway so no harm in trying.

 

ill take some 0.35mm wire, strip the insulation off it and remove a single strand from it and use this.

the strands are 0.2mm each.

Thanks for te info. I'll follow up this thread

Indeed, I had to replace my AQS twice. Fortunately, one has been refunded since it was still under warranty.

14 hours ago, Breezy_Pete said:

I'd have a go at repairing one, under the microscope. Might be quite tricky, but could be fun to try.

Probably wouldn't use gold wire though, unless someone wants to treat me to 10cm of 0.1mm for £32 https://www.ebay.co.uk/itm/114870867902 😁

 

 

 

 

That's a pretty impressive hike on the price of gold!

15 hours ago, Bap33 said:

Thanks for te info. I'll follow up this thread

Indeed, I had to replace my AQS twice. Fortunately, one has been refunded since it was still under warranty.

Do you still have the new broken one? And what part number and revision is it?

 

5 hours ago, ApertureS said:

Do you still have the new broken one? And what part number and revision is it?

The original one was a D version. I threw it away upon replacement. 
The 2nd one was a D version too. I had to send it back for Quality control to be refunded. Thus I don’t have it anymore.

The 3rd one is a F version. It’s currently on my Mk3 and working well so far… 🤞

Thus, sorry, I don’t have any broken one left… 🤷‍♂️

On 24/10/2024 at 19:16, ApertureS said:

What do you mean turned on? 
All air will always go through the pollen filter whether it’s on recirc or not.

Sorry ApertureS, I meant the aircare setting. I'd of thought it would come on by default at times to keep the air in the cabin more filtered but it always needs turning on if you want it.

So it's the same as using recirc every now and then?

The OEM air quality sensors are made by Amphenol SGX Sensortech. The make a few different sensors that detect different gasses but the AZ65A seems to be the one most suited for air quality sensing in vehicles.

They can be purchased from Mouser or Farnell for around £30+VAT which is significantly lower than the OEM labelled sensors...I wonder if they're a straight replacement?

I've already replaced mine, but if it goes again...I'll probably give this a punt.

SGX - SGX Sensortech Sensor

Edited 1 January1 Jan by NikiB

That appears to be identical to the Ali CN one I installed last week.