Did they fail to meet the CARB standard, or did the just "cheat to get a better grade".
If you're asking about what VW did,
The agencies charged that the electronic control module (ECM) in the vehicles in question—roughly 482,000 diesel passenger cars—sold in the US since 2008—contains software that detects when the car is undergoing official emissions testing. Based on that ability, during EPA emission testing, the tainted ECM ran software which produced compliant emissions results under an unique ECM calibration. At all other times during normal vehicle operation, the vehicle ECM software ran a separate road calibration which reduced the effectiveness of the emission control system (specifically the selective catalytic reduction or the lean NOx trap).
As result, emissions of NOx increased by a factor of 10 to 40 times above the EPA compliant levels, depending on the the of drive cycle, the agencies charged.
BTW, your Passats wouldn't be affected (only 2014-2015 MYs), just the A3 (2009-2015 MYs).
VW attempting damage control, via GCC: http://www.greencarcongress.com/2015/09 ... -vwag.html
On Sunday, Volkswagen Group CEO Prof. Dr. Martin Winterkorn said that Volkswagen does “not and will not tolerate violations of any kind of our internal rules or of the law”, and said that the company “will cooperate fully with the responsible agencies, with transparency and urgency, to clearly, openly, and completely establish all of the facts of this case.” Volkswagen has ordered an external investigation as well.
The Board of Management at Volkswagen AG takes these findings very seriously. I personally am deeply sorry that we have broken the trust of our customers and the public.
The trust of our customers and the public is and continues to be our most important asset. We at Volkswagen will do everything that must be done in order to re-establish the trust that so many people have placed in us, and we will do everything necessary in order to reverse the damage this has caused. This matter has first priority for me, personally, and for our entire Board of Management.
—Prof. Dr. Martin Winterkorn
The pounding will continue for months, just one more thing to distract Congress from more important business.