Weird fault code

[pole]

Please tell me if you ever encountered this fault (discovered at the shop randomly, at a routine inspection) that left them baffled, they said, quote "we never saw this code before".

The code is as per picture attached, and it's described "engine speed monitoring difference between camshaft and crankshaft too high"

They basically said that if that were true, the car would run like absolute shit, as the timing chain would be out of place, also it should not start at all if one of the sensors was kaput. But the car runs perfectly fine, starts fine, all is well, I would have not known about this unless they didn't read the codes, no CEL, no nothing.

They advised I should do a firmware update at the dealer at the as they suspect it's a software issue/glitch, not a real problem.

It's a 2016 X3 B47 2.0 diesel xdrive.

edit: the mileage is in Km.