One problem related to horn assembly has been reported for the 2008 Volkswagen Jetta. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2008 Volkswagen Jetta based on all problems reported for the 2008 Jetta.
Drivers side door lock actuator failed to lock or unlock the door, alarm horn fails to sound when alarm is activated. Rear driver's door lock actuator failed to lock or unlock the door. The rear drivers door doesn't have an external key hole to unlock door and the only way to open the door is from the inside. In the event of an accident with a child in a child safety seat, this could result in a delay of removing the child from a potentially dangerous situation. The Volkswagen manufacturer/dealership charges between $450 to $550 per actuator. After an extensive search of the internet and numerous forums, this actuator repair is more common than Volkswagen would like anyone to believe. This part is kept in stock at dealerships and they are vague when questioned about the frequency of repair. This appears to be more a problem with newer models. I've owned a used 2003 vw Jetta for over 5 years now and haven't needed an actuator yet.