Passat Sedan: antitheft system instituted 2001 and up
Passsat Wagen: began using antitheft in 2003
Cars have had the Megamost Chip in the head of key far earlier. I do not have confirmation, but believe this was used by car to identify which driver, and thus the radio, seat position and other presets would be set up for that driver's key wheninserted in ignition.
Chip detectors will all recognize a chip, whether the car has a system in place or not.
As far as I know, only VW/Audi/Porshe have had chips before actual systems.
Contrary to other postings, SOME cars will allow a nontransponder key to work for a set number of times, FOLLOWING the use of a valid transponder key.
This feature has caused issues when programming keys, and testing them to be sure they are programmed in!
So, as far as all my resouces indicate, you do NOT have an antitheft system.
One less idiot light to have repaired!