Update:
I didn’t get a chance to remove the error before it went into service to do all the other things, so I asked them to have a crack at disabling it. They didn’t make any progress I’m told.
I will try put it to rest mode overnight tonight and see how it goes, although I don’t know if I can rack up 4.5 hours of driving to test(is it enough to leave the vehicle idling?)
The dummy VDO head might be a great option! Do you just unplug the old one and install the new?
Also, when calibration time comes, does the tachograph complain about that, regardless of out of scope?
Cheers for everyone’s help! I’m incredibly grateful.