Tachograph accuracy

Apologies, I’ve asked this before but I’ve forgotten the answer and I can’t find the thread now.

How accurate does the UTC fixed time on a tachograph need to be? I drove a truck this week and the tachograph was nine minutes slow. Is there a limit as to how far out they can be?

That does seem significantly out, which shouldn’t happen, as they are required to be calibrated in a registered workshop every so often. I would report to the operator…

20 minutes if my memory serves me correctly.

It would take you 9 weeks to adjust it to right time as you can only do 1 minute a week

AF1:
20 minutes if my memory serves me correctly.

It does

Yes as previously said 20 mins after that it will need a complete calibration ,crazy but true …Though it can cause chaos if jumping from truck to truck with time overlaps

norb:
Yes as previously said 20 mins after that it will need a complete calibration ,crazy but true …Though it can cause chaos if jumping from truck to truck with time overlaps

Yes, I’ve had that in the past, tacho wouldn’t let me log on because I inserted my card earlier than the time I ejected it from the previous truck.