Ignition Key With Radio-Frequency Remote Control, Checking
WARNING: This page is about a different car, the 2015 Volkswagen Passat, 2014 Volkswagen Passat, 2013 Volkswagen Passat, and 2012 Volkswagen Passat. However, it is still accessible from the selected car via links, so may be relevant.
-- Ignition Key with Radio-Frequency Remote Control, Checking, use the Vehicle Diagnostic Tester.