@WelshGas I got my car mechanic to change all four sensors, as per the article you linked. That went well enough, although he had to disconnect the hydraulic hoses to do it as there was no way to remove the sensors without possible damage to the hydraulics. No problem, he refilled the special hydraulic oil and then opened the roof just fine.
However, now a new "Fault 1000" error appears when he tries to close the roof. It refuses to close. He intends to release it manually and then strap the roof down, if he can't work it out by later today.
Is there anything you can think of that might help?
He's been checking forums but found nothing that worked since yesterday, he tells me. He did call up a specialist camper workshop this morning and they told him that normally new sensors come with new wiring. The BMW sensors came on their own. He did not change the wiring, just the sensors. So, perhaps it's that, but he says it looks like it's not easy to change the wiring as it goes inside the van.
At this moment it looks like I'll probably have to take it to VW and they will insist on replacing the sensors again for sure. I'd like to avoid double charges if I can help it.
Any help or pointers are greatly appreciated.