Quote Originally Posted by prise View Post
I dropped the car off today and was called back 4 hours later to say it was they had been able to perform the test this time with advice from head office and the the system appeared to be working correctly. I asked how the system had been tested and was told that the official test procedure involved the use of a small amount of LPG to trip the sensor. I was also told that they had performed the same test on a new vehicle to confirm that it switched to recirculation in the same way. I have no knowledge of the test procedure they used so I don't know if it is able to test the sensitivity of the sensor or whether it only tests for functionality

The customer service rep had no explanation for why the system doesn't go to recirculation when driving behind badly smoking exhausts (burnt oil and petrol smell) so given they diagnosed a different fault first time round and then concluded on the second visit that it was working correctly I have concluded that they were not familiar with the system and the test procedure.
You can conclude whatever you want but they told you the Volkswagen method of testing the sensor for operation which they performed so I'm not sure what else you want them to do short of fly the sensor to the manufacturer for testing the same way.

Is the air quality sensor only useful if I drive through a gas leak!
No but it's not some magic sensor that works like you expect it to. A basic portable hand held gas detector starts at around $1500 and they can easily reach $6000+. The sensor in the Golf sells through the dealers for under $150.

Information on how the sensor operates is here - Climatronic Air Quality Sensor Operation and Location