Register on one of these sites, enter your VIN and search for your part's OEM number. Here is the list:
Citroen: http://service.citroen.com
Peugeot: http://public.servicebox.peugeot.com
Hyundai: http://service.hyundai-motor.com
Audi: http://erWin.audi.com
Ford: http://etis.ford.com
Mercedes: http://service-parts.mercedes-benz.com
Renault: http://infotech.renault.com
VW: http://erWin.Volkswagen.com
Opel: http://gme-infotech.com
I hope it helps