The Body or Convenience (non critical) CAN on VAG I have always known to be 2 twisted wires and Mirror image however it will run in single wire mode if one side is damaged and give a fault code.
VAG do extensively use K line & LIN too which are single wire. Add to that MOST Fibre Optic, Wireless, Infra Red, Bluetooth, Wireless, Radar .... ..... ..... Just because our job is not hard enough I guess.
So, for example, a 2013 VW Golf worth a few £k has more Networks for it to function correctly than whole Countries or Continents. Puncture two of its (if not runflat) tyres and it is ruined, a brick, absolutely useless !!!
It has to be a conspiracy to get rid of us Technicians, Diesels (Money Makers) are slowly going, Petrols are in the minority and can always be fixed with a Coil Pack, Hybrids and Full Electrics don't go Wrong.
The end of the diagnostic technicians world is how far away ???
I have seen this fault numerous times and usually a good whack on top of the cluster will get the car started/diagnosed and into the work shop ready for repair
For those who find this thread in the future: on all Mk2 and Mk2.5 Focuses we have seen this problem can be solved by resoldering the pins on the connector socket on the back of the IC. With a magnifying glass you can usually see the broken solder joints. There are some fun gotchas in taking the IC apart but it's absolutely doable in house if you are capable with a soldering iron. The IC incudes the terminating resistor of the CAN bus, so when these pins are intermittently connected the bus becomes unstable. I've also seen this same problem on the Kuga and S-Max of the same era. Symptoms we have seen so far include:
Odd speedo behaviour
Engine malfunction warnings
Engine failing to start with no errors
Alarm going off
Wipers not operating or operating on their own
Engine claiming it is overheating and going into limp mode when it isn't
But frankly given the corrupted messages almost anything is possible. Temperature change outside can affect the behaviour.