Causes of CAN faults:
WARNING: This page is about a different car, the 2008 Porsche Cayenne. However, it is still accessible from the selected car via links, so may be relevant.
- No or incorrect basic setting/adaption (control module)
- Short circuit to B+ (CAN lead)
- Short circuit to ground (CAN lead)
- Short circuit with respect to each other (CAN lead)
- Open circuit (CAN lead)
- 'High' and 'low' confused (slot in connector, or wires separated and repaired incorrectly)