This explains what the recall is:
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Recall Details
For affected vehicles sold as used by Volkswagen after internal use, some modifications were performed while owned by Volkswagen which affect compliance with federal regulations. Vehicles that are not compliant may pose safety risks. Some of these vehicles cannot be repaired, and if so Volkswagen will repurchase these vehicles. If the vehicles can be repaired, dealers will repair the vehicles to full compliance status free of charge to resolve the concern.
Our Quick Take
For affected vehicles which were sold to customers after being used for internal use at Volkswagen, some vehicle modifications were made that prevent them from being compliant for applicable federal regulations. These software and hardware modifications may or may not be able to be repaired. If vehicles do not meet all regulatory requirements, there could be an increased risk of crash, fire or injury.
What Should You Do?
Recall repairs on your Volkswagen must be performed by a Volkswagen dealership. Volkswagen will notify known owners of affected vehicles beginning in July, 2018. If you do not receive a notification, but wish to check to see if your vehicle is included, please contact one of your local Volkswagen dealerships. They will also check for any other incomplete recalls on your vehicle. For best results, be prepared to provide your Vehicle Identification Number (VIN) to the service department consultant you speak with."