Vosa and the police will commence their enforcement activities for all drivers from 1 July, after exemptions were introduced for those possessing faulty tachograph cards.
Problems arose in March when both driver and company cards began to fail without warning.
The DVLA said the problem was related to the cards’ microchips, but it did not know why the types of errors being reported varied.
It says it has now written to all drivers with cards issues between 24 March 2007 and 31 August 2008 explaining that some are malfunctioning and would they return faulty ones in order for them to be replaced. A final reminder is being sent out this month.
Affected drivers were exempt from Vosa prosecution while they waited for replacements, but this is now due to end.
“The should have responded if they have a card that’s faulty,” says a DVLA spokeswoman. “We have done all we can do to alert them. We are pretty much on top of it now.”