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I just scanned my car and was surprised to see this:

Address 08: Auto HVAC Labels: Redir Fail!
Part No: 4B0 820 043 AM
Component: A6-Klimavollautomat 0105
Coding: 00000
Shop #: WSC 00000

1 Fault Found:
01592 - Air Quality Sensor (G238)
57-00 - Electric Circuit Failure

When I went back to the module to clear the DTC, I got a time-out error. In fact I had to try and connect several times before it would finally connect. The DTC won't clear.

Looking back on previous logs from autoscans, the HVAC is completely missing. I'm guessing that the vagcom tried to connect to it, couldn't and assumed the car didn't have one.

2 questions:

1. What an earth is an "Air Quality Sensor"
2. Should I be concerned about this module playing up considering that I can't find anything that doesn't work as it should...

Do you have the automatic re-circulate option?

That uses an "air quality sensor" to decide when there are fumes in the incoming air and switch to re-circulate mode.

I believe I do, but I couldn't say for sure. Surely an RS6 would have that as standard? It's not so much the air quality sensor that worries me as the difficulties in connecting to the HVAC with the vagcom.

I'm guessing that the automatic recirculate is the recirculate button with the little A in it. In which case, yes I do have it.

Is it worth replacing the Air Quality Sensor?

What version of VAG-COM are you using, and what lead do you have? If you have a serial lead are you using a USB to serial converter?

USB to serial converters are not supported because of problems with unreliable connections.

I know that some modules (e.g. the phone module) can be very "fussy" - that module was really difficult to reliably connect to prior to the 6xx version of VAG-COM.

Air Quality Sensor? - I have the auto re-circ (an option) on my RS4 and find it works well when I'm behind a petrol car but it's unable to detect the emissions from a diesel car/lorry/bus. Is it worth replacing the sensor? - do you find yourself having to hit the manual re-circ button often?

I'm using the latest version of VCDS (805) with a genuine Ross Tech HEX-USB+CAN cable. I wonder if the faulty G238 could be causing the communication unreliability with VCDS.

Until you asked me, I didn't even know that automatic recirulation existed! So I won't miss it. I'm just anal about having everything working on my car That and seeing if it improves communication with the HVAC...

It looks like quite a cheap part. Do you know if it's reasonably accessible?

Shoppinit wrote:Do you know if it's reasonably accessible?

Sorry I don't know, anyone got access to ELSA or the Bentley manuals?

Shop did you ever sort this out?,mine has just come up with same error,any idea whats involved in changing it or cost

Wow, blast from the past.

Yeah, I changed the air quality sensor and the DTC went away. I think. The Vagcom doesn't like going into the HVAC - I think it's scared.

It's a really easy fix. Takes about 3 minutes. I think it cost about £20 but I could be imagining that.

Cheers , will get my hammer out and sort it.

It's just attached to the pollen filter. It hangs off the edge of the filter holder, IIRC. You should be able to identify it pretty easily if you get a new part. Let me know if you need any more info.