On Sat, 19 Sep 2015 00:19:10 +0000 (UTC), Ewald Böhm
wrote:

Apparently Volkswagen/Audi cheated on the USA emissions tests since
2009 to 2015 by turning off the EGR to lower nitrogen oxide emissions
ONLY when the car was being tested for emissions.

REFERENCES:
http://blog.ucsusa.org/volkswagen-ca...cle-recall-887
http://www.engineering.com/AdvancedM...EPA-Tests.aspx
http://hothardware.com/news/vw-inten...-482k-vehicles
etc.

My question is HOW did the car *know* it was being *tested* for emissions?

My guess is that anytime something was connected to the diagnostic
connector the car turned on all the emissions systems. I know that
here in AZ they have been doing the emissions test for cars for quite
a few years now by plugging into the diagnostic connector and reading
the computer looking for pending codes that haven't turned on the CEL.
If you have more then a couple pending codes you fail. My PT is a
2009 model and it's always been tested that way so the time frame is
certainly doable.